A few theories, which will probably be discarded as soon as anything significant happens.
First of all, uu is, in all likelyhood, going to be red in some way. So far, we know that green is the colour of Space (Jade's text colour, Kanaya's blood/text colour, and Calliope's attire/body?) and that red is the colour of Time (Dave's text colour, Aradia's original blood and text colour). Wait, we already know he has red blood. Oh well. More supporting evidence, I guess.
Secondly, UU mentions that a hero of Time and a hero of Space are needed for a complete session. However, the post scratch kids lack either of these. Whether this actually matters, as the post-scratch kids are in a null session, is unclear, but this may be the reason for the cherubs, to act as the Heroes of Time and Space for the kids as well as their own. Anyway, I have no idea how that would actually work, just throwing that out there.
Finally, a connection between Calliope and Hussie? It's implied that uu also has dual strife specubi, and the scepter/Machine gun weapons Lord English uses fit Calliope's description of his weapon(s) being a bit more heavy handed than hers, and AH is shown using the same white magnum and wand that Calliope uses, not to mention wearing the same style clothes and cosplaying as a troll. Wherever AH and Lord English are in the A6I2, could it be the land where UU and uu are transported to upon begining to play Sburb or whatever their variant is. It is possible that uu kills UU, and AH somehow finds her stuff, but until I have further evidence I'm just going to assume that Andrew Hussie is confessing to being a bright green alien.