In my headcannon, Sunny finds Twylight who’d thawed out. Grey and broken, her powers gone. Ashame coz her sins such as MArer Do Well, the Walking Dead, pupeteerign Rainbow in the division with Rarity and the cheerleader, betraying the CMC fro Cozy Glow, abusing Spike in the owl affair, doubting Pinkie in the hydra and parasprite incidents as well as betraying her, scaring Flurry Heart, prejurdicing Dyscord and Capper as well as Trixie and Zecora, the Lesson Zero incident, and more help Opaline and enarly end life. And Marer Do Well who is forge from the darkness within her, Applejack, Pinkie, and Rarity reveal her sins. But instead of turning on her, Sunny reacts with compassion as Twylight did for Fizzlepop Berrytwist; choosing forgiveness and hugs Twylight to comfort her. And she gets angrey with Marer Do Well for her lies. And Twylgith regains ehr pwoers for saving Sunny; an act of self-sacrifice. And reunites with her revived kin.
In my headcannon, the two forge a bond similar to Twylight with Celeztia. It be grand ifTwylight taught Sunny. And also if Sunny help Twylight’s heart heal. And spend time with ehr including when they read books, enjoy hayburgers, sing, dance, and more.