I can't think of anything off the top of me head but I'll try and give you three things for each for now XD
Saxton:
-He can sleep while standing. A habit developed since he is always running missions and usually takes whatever few minutes of peace he can get to sleep.
-He's never had chocolate despite spending downtime buying take out. He eats take out cause he can't cook. Saxton never saw the need to cook so he never learned. I'll just keep that bit here even though it doesn't go with the previous fact XD
-Despite being 8'5" he moves around quite easily. He had a lot of training to handle his huge body before becoming a Guardian and that remained as muscle memory. His size doesn't help with going through small spaces though haha Also he gets nervous around smaller then average Guardians, he knows he won't hurt them but it's always a fear XD
Aya:
-She put in her second pair of arms herself over the course of three of her resets. She had to relearn everything, granted, but thanks to video logs she keeps of her work it doesn't take her long to pick up where she left off.
-Aya owns a Cabal carrier for a ship. She acquired it during the Red War and now uses it as a mobile workshop. How she acquired it is not a story she really tells though. Not a fun time for her.
-Aya only knows how to use handcannons. She can't handle anything bigger at the moment. Saxton was going to teach her but he always ended up being busy with Vanguard work. Aya doesn't mind though, she can wield two handcannons now and has become scary accurate with them XD
Also I don't know if I mentioned this before but these two are siblings. Adopted siblings X)
If any of you have anymore questions about them feel free to ask :D