Aw, poor little Five. I relate, since I hate crying and being sad so I cover it up with anger instead. I’m so glad that Allison and Klaus were there to comfort him. (Outside of this fic, I really wonder what happened to Vanya’s body in the first timeline/apocalypse as well.)

this is really sad especially considering how if he remains in his 13 year old body, and they they their 30 (or something)he will have to bury them again

This was interesting. I liked how you slowly brought out why the stone gazebo was worthy of note. It being one of the few things standing post-apocalypse was good. Five burying his siblings by it was also a cool detail. The way you described Allison's body was both heartbreaking and horrifying. Even more so that Five never could find Vanya's remains to put at rest. Allison noticing Five crying and her trying to comfort him even as he screams at her I liked too. Klaus showing up at the end there and the two of them forcing Five into a hug was kind of funny and I enjoyed how he gave into it in the end and how he sort of promises himself he won't burying them all again.
There were a few things that I noticed while reading:
"…he's thrown on a…nightshirt fluttering against Klaus's hairy…" Hm, this doesn't read quite right. I feel like maybe there was supposed to be a period after "nightshirt"? It would make sense for something like that to be there.
"He doesn't response, at first…" I think you meant "respond", not "response", yeah?
"…Allison and Klaus meet gazes together…" I feel like using the more conventional "met each other's gaze" would read better than "meet gazes together". Up to you, though.

This was a nice piece. Five was having a hard time, and in true sibling fashion, he gets comforted against his will. :)