Here's my theory:
Chris is part of a group of outcasts from both sides. They may not be the same as the Avatars. I think that events that happened during S4 and S5(the vanquishing of The Source, the Attack of the Titans, etc.) have broke down discipline on both sides. No longer could the Elders control all the Whitelighters and there's no true Source to get all the evildoers in line (not that the last could but hey...). So we have a bunch of "free agents" who've gotten together for some reason. I think these individuals in the future had become so powerful but Wyatt would represent a big threat to their power. My thinking here is Wyatt would be the one who would help restore order on Earth and the Elders would give him needed authority in the future.
So the outcasts attempt to undo Wyatt's future work. They figure they send someone back into the present, believing that the Charmed Ones would not learn of the forming of the outcast group until it's too late. That's where they give instructions to Chris to never reveal their ultimate plan. He's sort of the "first wave" of troublemakers. If there's a chance that they'd be found out then, the thinking goes, make the Charmed Ones and Elders think that Chris is working for the Underworld. Meanwhile, Chris suckers the Underworld into believing he's going to help them when he really pins them against TCO's/Elders.
Anyway, that's my thinking on this. How would they get to Wyatt without him shielding himself and calling Mommy?! I have no clue but if my speculation is right they'd send someone else to finish the job...maybe a darklighter (but I doubt that). Well, I hope my speculation is right because that would be very 😎
