Peter stops slightly when he senses Stephen sit down, and when Stephen actually does press up against him. It helps a lot, and his silent sobs, while initially quite strong, fade as the minutes pass. He's lost in his own thoughts, lost in a vortex of blame and pain and just grief. Which is, as terrible as the circumstances are, better for him than his usual way of dealing with Bad Things, which is not dealing with them at all.

After Yondu, though, maybe it wasn't so bad to just let it all out.

He wants to pet the Cat, but he's not sure he can even bring himself to touch fur right now, but the purring is helping. Something kind and warm to simply just be there.