In my mind their relationship is like that of an older and younger cousin. Amicable except for the times when they happen to annoy the hell out of each other.
(I actually drafted this back when I played the demo and noticed them standing together in the background during the cooking cutscene) The thought of “what if, before Eleanor took charge, the rangers took turns cooking dinner when camping” amused me
Simon is banned from touching the stove ever since he and Lio (both 15 at the time) found this weird unknown mushroom and decided to cook it because “research!”. Cue the worst case of food poisoning in the history of Azuria for everyone involved. As punishment (for enabling Lio) Simon was delegated to dishwashing duty for the rest of eternity. Gaul’s eye twitches every time someone happens to bring up the incident (he was the one who was supposed to keep an eye on them but he turns away for five seconds and, by the gods, those two brats managed to mess up the stir-fry beyond recognition- )
