Piotr shows up and beats the snot out of Pete Wisdom for laying hands on "his" Katya. It goes downhill from there and ends up with Excalibur locking Piotr up until he calms down and they can sort it out. As was the wont with Piotr at this point, no one had had a clue what to do with him; Simplisitically put, he'd joined the Acolytes after noticing that siding with Xavier kept getting family members killed, and then left them after he was disillusioned by them.
The various members comes to try and see what's up with him, and when Kitty shows up he goes into drivel overdrive and goes on about how they were destined to be together. Kitty basically tells him to shut up, grow up and grow a pair, and realise that they were both kids when they had... whatever they had had 20 years previously (real time wise) and she had long since moved on. Peter was a different sort of person completely, but she had a much better handle on her feelings now, and was an adult, whilst Piotr was still pining after her like an embarassing 15 year old with a crush.