Transformers Bunny Farm

2. Starscream finds all the 'Cons not on duty in the rec. room clustered around the monitor at the other end of the room, laughing. When he walks in they start laughing harder. Before he can make some snarky remark and tell them off, however, he sees what they're watching: home movies. Of Skyfire and himself moving into their first apartment after graduation. Starscream is in shock (probably trying to figure out how they got their hands on videos he himself hadn't seen since before the war). The other Decepticons make fun of him while flipping through the other recordings - until they're shocked into silence by one of the last clips:

Starscream and Skyfire. Cuddling a tiny little sparkling.

This one makes me think of the first plotbunny in the post before this:

1. A new Transformer comes to Earth to join the Autobots in their battle with the Decepticons, but the young ‘Bot’s overly independent nature and deep hatred for the Decepticons, especially Megatron, becomes problematic. It would seem that their newest member has an agenda of their own, which centers around Starscream, only no one’s exactly sure how the two fit together. That is until it is revealed that the young ‘Bot is Starscream’s only sparkling, whom Starscream secretly left with the Autobots as a means of protection at the start of the war.

Although vox00 had a 1a. about Optimus remembering a one-night stand, I can't get that to work in my head and the more likely is that the sparkling is Skyfire's. Let's just say, my new OC muse, Soaringstar, has picked his non-bearing parent.