Find the Others is a quest in Chapter 17, "Deliverance from Chaos" in Final Fantasy VII Remake, taking place in The Drum. It has the subquests Find Barret, Use the Central Terminal, Research the 3rd Ward, 2nd Ward, 4th Ward, Rescuing Red XIII, To the Central Terminal, A Way Up and The Source of the Sound. Cloud Strife is separated from Tifa Lockhart, Aerith Gainsborough, Barret Wallace, and Red XIII, and the party must regroup.
Walkthrough[]
Cloud begins the quest alone. Head right and pull the lever nearby to create platforms across, then hop over them and proceed along a linear path to where Monodrives are fought. Use aerial attacks or spells to defeat them, then proceed along the path between the pods. A gap on the right of the pods leads down to a detour where a 
Poison Materia can be obtained. After this, return back and follow the route underneath a pipe.
Unknown Entity enemies are fought, and Red XIII joins the party as a guest character. He cannot be controlled, but will help Cloud in battle. The Unknown Entity enemies can be defeated in Cloud's Punisher Mode and with simple character abilities. After this, proceed up the debris to an area that is impassable. Use 
to call Red XIII to flip the switch on the other side, creating a path across. A bench and a vending machine are found nearby to heal, after which, continue down the path until Barret can be heard.
After heading through the gap in the wall, Barret will join the party, and Monodrives are fought along with a Mark II Monodrive. These can still be dealt with using character abilities, but are more durable, and can make themselves immune to physical damage, at which point simply use spells to defeat them. Once they are defeated, Unknown Entity enemies are fought, along with a M.O.T.H. Unit. This enemy repels melee attacks, meaning Barret should be used at first. It will charge up electricity for a potent attack; defend against this, and then use melee attacks from Cloud in Punisher Mode to stagger it.
Once the enemies are defeated, proceed through the door that opens. A treasure chest contains a the 
Twin Stinger weapon for Cloud; this weapon provides many materia slots and a mix of physical and magical stats. Proceed up the stairs on the right and command Red XIII to flip a switch on the other end. After a cutscene, proceed around the blue shielded control room and interact with a console on the other end.
Research the 3rd Ward[]
When the dialogue ends, choose the option to switch party, giving the player control of Tifa in a party with Aerith. As Tifa, follow the stairs up to a laboratory room, then follow the linear path up to a door marked 03, which is locked. Run to the left and pull a lever, creating a path across for both parties. Hop across the path to obtain a bottle of ether in a chest, then head right to a PHS console, and agree to switch parties.
As Cloud's party, after dialogue ends, head across the path to face a Blast-Ray and two Slug-Rays. Slug-Rays can be defeated with aerial attacks or blasts from Barret's guns, while Blast-Rays are best fought using spells or abilities from Cloud while it is not repelling him with wind attacks. Pull a lever on this platform to create a path to the center platform, obtain the Time Materia on the left, then interact with the ward 3 switch to open the path for Tifa's party. Use the PHS terminal on the left to switch to her.
With Tifa's party, head inside the ward, and pull the lever in the inner room, opening a gate outside. Run through the gate and defeat the Unknown Entity enemies with character abilities, then head through the gap in the wall. A mega-potion can be found in a chest on the right, and after proceeding further past several cages, several bloodhounds are fought. Tifa should combo her abilities together, while Aerith stays at the back providing assistance and spells. Her ATB Ward can also help Tifa link several more combos together. After defeating them, head underneath the gap and through a linear path and a zenene is fought. This enemy can be defeated with Tifa's ability combos.
After defeating the zenene, head inside, pull a lever to open a gate, then head into the next room and up a flight of stairs. After proceeding forward, two more zenenes are fought after Aerith and Tifa fall. Pull the lever on the eastern side of the room to open leading to a chest with a force bracelet, then on the western side of the room, a ladder can lead up to a chest with a mega-potion, though the path forward is underneath a gate. Follow this path and walk out of the exit, and the ward behind will close. Head down the stairs on the right to a lower level, then proceed down the stairs south for a chest with an ether, and head back north to follow the path forward. Three Sentry Launchers are fought here; guard against their attacks, and use Tifa's abilities and Aerith's spells to defeat them, then proceed up the ladder and pull a lever to create a path across. Run across the path and use the PHS terminal to switch to Cloud's party.
2nd Ward[]
With Cloud's party, open the ward 2 door at the central terminal, then head across the bridge then head left across the path created by Tifa's party, obtain the mega-potion from the chest on the left, and head inside the ward. Run through a linear path until two zenenes are fought, best defeated with Cloud and Barret's abilities. Head through the door on the right into a corridor, then then right again in the wider corridor to pick up an astral cuff, and then left to proceed to a room where an M.O.T.H. Unit and several Shock-Rays are fought. Aim for the Shock-Rays first with and aerial attacks abilities, then focus down the M.O.T.H. Unit when its spinning blades stop.
After the enemies are defeated, wait for the dialogue to end, heal up, and head through the door on the right to lead down to another room. After a cutscene, two Sledgeworms are fought. These enemies will warp between different points, and are weak to Lightning Materia spells. Deal enough damage to them to pressure them, and then lay into them with Cloud's Punisher Mode and Barret's abilities such as Maximum Fury to stagger and destroy them. After defeating them, head through the gap created by Red XIII and up the stairs to a cutscene. After meeting up with Red XIII, run forward to the next room, pick up the chain bangle in the end corner, and use the staircase up to a higher level.
At the higher level, follow the linear path forward until a cutscene commences, following which the Brain Pod is fought. This enemy is also weak to lightning elemental attacks, and its Noxious Whirl will inflict 
Poison on everything nearby. It will remain stationary for most of the fight, however, meaning Cloud can use Punisher Mode while Barret stays at a distance to use abilities. After sustaining damage, Barret and Cloud will be stunned as the Brain Pod creates clones of itself to surround them, all using Noxious Whirl. After this, use area-of-effect ground attacks such as Cloud's Triple Slash or Blade Burst, and Barret's Smackdown to destroy the clones, then destroy the original target after. Once it is destroyed, proceed forward and the ward outside will close. Run up a set of ladders to lead to the fourth ward.
4th Ward[]
Outside the 4th ward, use the bench and take the staircase down on the right, then command Red XIII to flip the switch on the other end and create a path across. After he does so, Unknown Entity enemies are fought; defeat a few for a cutscene, then head across to the PHS terminal and switch to Tifa's party.
As Tifa, hop across the pods to another platform, then fight the sledgeworms here. Against them, use spells as Aerith, and make use of Tifa's Unbridled Strength to use Omnistrike and pressure them, and keep using her martial techniques with Unbridled Strength to get in damage before it leaves. Once they are defeated, proceed down the ladder and defeat the enhanced shock troopers using Tifa's abilities and Aerith's spells, then head through the gap and fight the Unknown Entity enemies with Red XIII. After they are defeated, a cutscene commences. Run down the stairs and at the end of the platform, ask Red XIII to flip the switch on the other end then cross. Approach the locked elevator for some dialogue, then use the lever at the edge of the platform to create a bridge to the central terminal. Defeat the Slug-Rays and Shock-Rays with Aerith's ranged attacks or Tifa's aerial attacks, then head to the central terminal and pull the lever for ward 4, and use the PHS terminal to switch to Cloud's party.
As Cloud, hop across the pods, defeat the Unknown Entity enemies, and then use the ladder up to the 4th ward. In the tunnel inside, head left to obtain the two mega-potions in the chest, then head right to find a lever. Pull it, then proceed forward down a ladder and up another into a red tunnel. After a cutscene, the swordipede is fought. This is a flying enemy has no elemental weakness, and powerful melee attacks. Shoot it with Barret or use Cloud's aerial attacks, and cast spells while avoiding its melee attacks.
After swordipede loses a third of its HP, the player controls Tifa's party (holding 
during the cutscene allows the menu to be used just before battle). While it is flying at a distance, aim at it with Aerith, while Tifa uses her Unbridled Strength and waits for it to be slow to use martial techniques and damage it. It has two abilities that speed around the terminal; Live Wire can be guarded against, though Saw-Tooth Spin needs to be avoided by staying on the inner or outer side depending on where it is spinning. Avoiding its attacks is crucial, though once it completes an attack, it will become pressured and vulnerable. Once pressure ends, it blocks Tifa's attacks, meaning Aerith should be used. It will later use Energy Volley, which drops electric bombs that can be guarded against. Once it is defeated, a force bracelet is obtained, and a cutscene commences.
After it is defeated, Tifa is controlled again. Follow Aerith to an elevator, then after using it, follow Aerith again and pull a lever. After this, a party of Cloud, Tifa, and Aerith is created. Run back to the elevator Tifa arrived in, activate the button, then follow Barret and Red XIII. After some dialogue, follow the purple blood on the ground to an elevator. Activate it and agreed to go inside to proceed to the next quest, "The Ominous Trail".
Hard mode tips[]
In most early battles prior to Swordipede, equipping 
Elemental Materia with Lightning Materia on armor is effective against most enemies as it mitigates damage from enemies' lightning attacks (including the Unknown Entity's Thundaga as well as many attacks from the machine enemies), and also grants access to lightning spells, helpful against many of the robotic enemies. In the 3rd Ward, elemental materia can be paired with Ice Materia on weapons instead.
For Swordipede, pairing lightning and elemental materia works again to protect against or heal from many of its attacks. When switching parties, ensure to hold to access the menu and give it to Tifa and Aerith. Avoid spending too much MP, as other bosses appear in the chapter. Aerith can cast 
Thundara from Arcane Ward to deal damage while not expending too much MP. MP Absorption Materia can also be paired with lightning materia for her, though she will need to be more careful about avoiding Swordipede's first few attacks, which are lightning-based.
Defeating Swordipede will grant Aerith the Telluric Scriptures Vol. XII.