[quote=@AGenericUser]Class System: My bad on this - I probably should've went a bit more into detail. While his appearance would change, I feel like it would be limited to armour and equipment, depending on the class, while his physical body underneath stays the same.

On the topic of wings and gills, if he can create a gun, I guess those would be possible...[/quote]
The way I'm reading this is that Kai would basically have five forms he could switch between. Speed, Strength, Defence, Air and Aqua. These would appear on his body as pieces of equipment, such as powered boots for speed, gauntlets for strength, body armour for protection, glider wings for flight and a rebreather for underwater breathing.

While any one of these can be active at any time, he wouldn't be able to combine them so if he chose to have his 'running shoes' on he'd be able to move quickly but would have less protection and wouldn't be able to bring as much firepower to bear.

His weapons would also be linked with these modes, with perhaps the sword and pistol his baseline choice and things like a pair of pistols for his speed mode, a heavy doublehanded sword, axe or warhammer for his strength mode, and so on.

Could he possibly switch between them for interesting combination effect though, for instance using speed and running off a high cliff and then switching to the glider in midair to float a fair distance, before switching to the strength mode to power bomb an enemy? Or would it be more a case of him having to completely shutdown one class before using another; so he'd use speed to boost himself off a cliff, then deactivate and freefall for ten seconds before activating his glider to move into position then shutdown again and start to plummet towards the enemy and activate his strength mode just before 'landing' to maximise his impact?

[quote=@AGenericUser]Personalities: ...and someone would be able to forcibly swap Kai between them...[/quote]
It'd be an interesting feature to work with if you did keep it, especially from a roleplaying standpoint. You could even make it that each of his different modes had a distinct personality associated with it, similar to the way Ben 10 transforms into new creatures with their own personality traits, but all of whom are still 'Ben' at the same time.

He'd have to be [i][b]really[/b][/i] careful about what he said around Kiki though, unless he wanted to have his personality randomly shifted for a few hours with a wave of her hand.

[quote=@AGenericUser]Also, his name was originally Kal, but I really like Kai as a name, so I think I might just have to take that up as his new name.[/quote]My bad (or good..?) I'm working off a smart phone right now and the screen's a little small. Misread Kal for Kai. :)