In Solitue, Reunite with Tifa, Finding Wedge, and Beyond the Fracture are quests in Chapter 13, "A Broken World", in Final Fantasy VII Remake. They take place in the Underground Test Site. After Cloud Strife, Tifa Lockhart, and Barret Wallace find a cave-in at the remains of Sector 7, they fall through a gap, taking them to the bottom of the test site.
Barret Wallace is the party leader for the following quests. Use the bench to heal and check Barret's equipment. From the starting point, head south, and hold to fire Barret's gun at the rubble. After this, bugaboos are fought, and can defeated with normal attacks and Barret's Overcharge. Wererats are fought afterwards, and are likewise simple to defeat. Further down the tunnel is a fork in the road; shooting debris on the right leads to a treasure chest, while shooting debris on the left leads to the next room. Here, two bloodhounds are fought; these are more durable enemies, but can nonetheless be dealt with using Barret's Overcharge and his spells.
Head forward and up a ladder, then to the left, defeat the bugaboos and shoot debris above, clearing a path to a treasure chest with two mega-potions. Head further in, defeat the bugaboos and bloodshed, then climb the ladder up and into a cave. Destroying the debris left leads to a healing carcanet, while the path right proceeds down the quest route. Gorgers are fought here, but are once again simple enemies. At the end, Barret can shoot a spinning turbine to create a path forward up a ladder. Climbing the ladder leads to a cave with many boxes on shelves which Barret can shoot. A staircase is found at the end of the tunnel, and after heading up, Barret will spot Tifa. Head left up the stairs and around, then shoot a container in front of Barret to drop it and destroy a nest. Head back down and left, following the route around to meet her.
After reuniting with her, Tifa will join the party. Take the path right and up some stairs, then shoot at the turbines to create a safe passage forward. The left turbine creates a path to a treasure chest with an ether, the right turbine leads to a dead-end with boxes, while the middle proceeds forward. Inside, a bloodhound is fought; in addition to Barret's abilities, Tifa's Unbridled Strength martial techniques are effective against them. Shooting the safes around cages can net items; one cage contains an Ice Materia orb, while another has a chest with a turbo ether. Up the stairs, another cage to the right contains a Warding Materia .
Climbing a ladder proceeds forward, where a Monodrive and a Cutter are fought. Equipping Lightning Materia can be helpful against it. The Monodrive is easily defeated by Barret's Overcharge or or Tifa's martial techniques, while Cutter is more challenging. Cutter has powerful melee abilities, and should be avoided when charging them (at which point switching to Barret is ideal). Casting Thundara can pressure it, and Tifa's abilities and martial techniques can build its gauge, while Barret uses Lifesaver to absorb damage, and fires at it from a distance.
Once both are defeated, use the ladder down right and proceed to where bloodhounds and varghidpolises are fought. Bloodhounds require the same tactics as previously, while varghidpolises are similar and can be defeated with Tifa's techniques. Follow a winding staircase up to a platform where many bugaboos are fought, and defeat them with Barret's ranged attacks. When clustered together, Tifa's abilities, such as Divekick and Omnistrike, can take many out at once. Take the stairs up and use the bench to heal. The "Main Theme of FFVII" disc can be bought at the vending machine, along with previously available items. Before proceeding, equipping the Ice Materia can help with the next encounter, and unequip lightning materia. Ensure both characters have the Healing Materia. Shiva should also be equipped.
Unknown Entity and Failed Experiment boss
Head through the gap in the damaged gate towards Wedge, commencing a cutscene. After this, many Unknown Entity enemies are fought. These enemies are numerous and fast, but relatively weak. Ice spells can be effective against them when clustered together, though Tifa's abilities, such as her martial techniques, Divekick, and Starshower, can also deal area-of-effect damage that can defeat many of them when clustered together, and Barret's Overcharge can defeat them when they run at range. When more appear, they will be running at a fast pace, meaning it is better to control Barret and shoot them.
After swarms continue to appear, Barret suggests Tifa close the duct to stop them appearing. Tifa can run to the stairs, after which a cutscene commences, and the Failed Experiment arrives. For the first phase of this boss, Tifa is on a platform while Barret is on the ground below. Tifa should defeat the Unknown Entity enemies quickly using abilities with area-of-effect by destroying them in clusters. Later, Barret and Tifa must defeat the Failed Experiment while separated. If equipped, Tifa can cast ice spells while the Failed Experiment focuses on Barret, and while it focuses on Tifa, Barret can shoot for its appendage or cast his own ice spells. Crippling the appendage will pressure it, and using ice spells can significantly raise its stagger gauge.
After it loses a third of its HP, the Failed Experiment becomes more aggressive and gains the ability to seize characters, though Tifa is no longer separated from Barret. Destroy the Unknown Entity enemies first, then focus on attacking the Failed Experiment's appendage when possible. If the Unknown Experiments become immune to physical damage, simply cast Blizzard spells against them, or allow Shiva to destroy them if she is available. Again, destroy the appendage to pressure the Failed Experiment, cast ice spells on it, and then use Tifa's Unbridled Strength martial techniques to increase the damage it takes.
Defeating the Failed Experiment leaves the Mythril Claws weapon for Tifa, which builds her more towards magic damage, and a cutscene takes place. Following this, "Beyond the Fracture" starts and Cloud Strife joins the party. Barret should shoot the debris in front of him to create a path ahead, leading to another cutscene.
Hard mode tips
Because of Barret's low MP pool and the necessity to save MP for the final boss, early on it is better to build him towards physical damage. Regardless of if Barret is using melee or ranged weapons, it is helpful to equip him with Elemental Materia and ice materia, particularly against the more durable bloodhounds. With a ranged weapon, by equipping him with First Strike Materia, Barret can open every fight with Overcharge followed by Maximum Fury; on melee weapons, this can be Overrun followed by Smackdown instead. Equipping the Salvation Badge helps healing spells go further if used when the target is in low health.
When Tifa rejoins, she becomes a higher priority for elemental and ice materia, due to her greater Attack Power, while Barret can focus on a tanking role with Provoke Materia. Tifa's Starshower is effective against the bloodhounds and the Cutter (though should she equip lightning materia with elemental materia instead of ice materia here), while Barret can use the same tactics as before.
Against the Unknown Entity and Failed Experiment, area-of-effect damage is ideal, meaning Tifa equip Deadly Dodge Materia, and Barret benefits heavily from equipping a melee weapon using Smackdown to destroy waves, though he must use spells for distant enemies. On Tifa, pairing Deadly Dodge with HP Absorption Materia can be beneficial, while Barret can pair ice materia with hp absorption. Tifa should also equip Parry Materia to help with her mobility against the quicker Unknown Entities. Pairing warding materia with Binding Materia to provide resistance to Sleep is also helpful. Once again, elemental materia can be paired with ice for damage, which is useful later in the fight when the Unknown Entities become immune to physical damage temporarily, though it can also be paired with lightning materia on armor to absorb lightning attacks.
Throughout the battle, casting Regen often is helpful, and Barret should use Steelskin and Lifesaver. Tifa's Unbridled Strength techniques, Divekick, and Deadly Dodge are especially useful for waves of Unknown Entities, while Barret's Overrun and Smackdown with a melee weapon are ideal. Against the Failed Experiment, Tifa should use Starshower and True Strike while Barret uses Blizzara and Blizzaga.
Defeating it will reward Barret the Sharpshooter's Companion Vol. VIII.