Disclaimer: a lot of stuff in here goes a lot worse than what I usually plan. In recognition of Exsilium: The RPG being for the Homestucks a somewhat more grimdark scenario and all that. If you examine this document closely, you'll find a lot of hints towards a much more optimistic timeline.

AUTUMN: No interaction until Salt the Earth, which leaves Eridan still wary. It's not until November that Kanaya and Roxy really get to a place of changing Eridan's mind at all.

WINTER: Conditions are worsening in Exsilium; multiple incidents provide Eridan reason to doubt the Initiative, and also botch Kanaya's attempts at winning him over with gifts.

SPRING: Conciliatory conditions are at last warming up enough that Kanaya qualifies as a less close confidante, maybe.

SUMMER: A new Homestuck character's arrival leads to the M-bomb's explosion, and a key piece of human CR (Takegami or Roslyn probably) is relocated in the fragmentation of the Initiative, which Eridan takes very badly. Despite this, Kanaya's loyalty to him and Roxy becomes increasingly fierce, perhaps especially so because the fragmentation incident also led to the scattering of the auxiliatrix keys.

AUTUMN: This is finally the point of "the D_M threads but in a game" - at least, between the increasingly frequent and unsuccessful Initiative missions. Conditions are getting worse and worse. Eridan probably actually gets physically hurt at some point in this process.

WINTER: Another hard one, and for Eridan the last straw. Even though conditions have finally reached a point of potential mutual romanticism, when he asks Kanaya and Roxy to come with him to the United Earth, they say no, and it's only the girls' more passive classes that prevent a repeat of Return to the core.

THE NEXT WINTER: Arrival of the PC in the game. Homestucks in their positions; Eridan away, Equius isolated, Meenah being Meenah, Gamzee-Kanaya-Sollux-Feferi unstable chain with tentative Roxy connection.

SPRING: Late in this season is your first potential battle with Eridan.

SUMMER: Early in this season is when Kanaya becomes recruitable - in this setup, your best chance is to have Roxy in your party beforehand and catch Kanaya creeping on her. The first time you encounter Eridan again with either of them in your party, he will come up with an excuse not to fight or to fight one-on-one. Depending on party composition (other people like Ros and Tak), your own relationship with Eridan, and how many times you've fought before this, you'll get the recruitment cutscene somewhere between time 2 and time 4. It's usually near the end of summer.

AUTUMN: This is when the transition to a party member moirallegiance *finally* happens, usually. Exercise for the programmer - determine proper point value spread for which combination of Kanaya, Roxy, Eridan, and the narrator ends up in the flushed quadrant.