Davesprite

Alternate Future Dave is the Dave from the doomed timeline where John was tricked by Terezi Pyrope into being killed by the Denizen. Upon splitting from the alpha timeline, it lost contact with the Trolls' Incipisphere, and Jade was presumably killed by her meteor. Not understanding the temporal mechanics at work, Dave and Rose assumed that the trolls, having achieved their goal of sabotage, had no further reason to contact them. With only two players remaining, the game was unwinnable.

We first see Alternate Future Dave on the Land of Heat and Clockwork four months into the future, where he discussed the deaths of his friends with Rose. Dave had alchemized some advanced gear including the Timetables and Caledscratch, and was high on the echeladder, managing to defeat challenging enemies with ease and style.

Davesprite
Dave's Kernelsprite was prototyped with the remains of the Rambunctious Crow by Jade, much to Dave's distaste. In Alternate Future Dave's timeline, it was second-tier prototyped with Lil Cal, a decision he deeply regretted.

After learning as much as possible about the game, this Doomed Dave used his Timetables to travel back to a period right before he prototyped his Sprite for the second time. He stopped John from skipping ahead to the Seventh gate and getting killed by his Denizen. He also prevented alpha Dave from prototyping Lil Cal, instead jumping into the Sprite himself after handing over his inventory.

As Davesprite, he gained access to the knowledge the game provides to Sprites. Although he is supposed to be cagey about the information, he promised to share it all with alpha Dave, simply because he "didn't really feel like it". However, alpha Dave declined to take advantage of the situation, never pushing Davesprite for answers to the game's larger mysteries. Davesprite also retained use of his iShades, as they were the only thing he didn't expel into a huge pile of punch cards before he jumped into the sprite. Davesprite used orange text while chatting on Pesterchum. He was upset when John called alpha Dave "Real Dave".

Other than that, Davesprite's personality was just like alpha Dave's, since he was simply Dave from a doomed timeline, and he claimed he would update Sweet Bro And Hella Jeff while alpha Dave continued his quest. The second-tier prototyping seems to have erased the rambunctious crow's personality entirely, as was the case with Jadesprite, so he displayed no avian traits apart from an ironic "caw caw motherfuckers."

After Dave stole Caledfwlch from a Crocodile Temple, Davesprite revealed he did the same in the alternate timeline. He defended Dave from a horde of Giclopses after Vriska put him to sleep, then used Dave's pendant to release himself in the same way Rose released Jaspersprite.

He then went to track down Bro, and found him in a duel with Jack Noir on the Land of Wind and Shade. He joined the fight and attacked Noir. During the fight, Jade entered the medium, resulting in Jack being prototyped with Becquerel. He quickly killed Bro and wounded Davesprite. His only remains were a pile of orange feathers and his pendant. Though he was presumed deceased, when Jade looks for the Daves in the Incipisphere with her goggles, the goggles don't count a certain dead Dave, but do count Davesprite. All this pointed to his ongoing survival, later confirmed when he revealed himself to Jadesprite on the Battlefield, now short one wing and wielding a complete Royal Deringer. He obtained this through "shenanigans" involving the denizen of LOHAC, Hephaestus.

As the meteors from The Reckoning reached the Battlefield, Jadesprite underwent her God Tier transformation. The new God Tier Jade that resulted shrunk down the giant meteor threatening them, then proceeded to shrink down the entire Battlefield and Davesprite along with the other Kernelsprites on it. She took them with her on her voyage through the Fourth Wall.

Personality
He is Dave, mostly. He appears a bit more bitter and worn out than Daveprime, partially because of having been through months of gameplay already, and partially because the others don't consider him to be a "real" Dave.