The question you want to be able answer about a potential character is: can I run with this? You can build up a character full of quirks and contradictions and then find he or she just doesn't move of their own accord- you're always having to cattleprod them from scene to scene. You know you're in this pickle when the thought of writing new scenes seems like a drag (or a bigger drag than usual). You want a character with LEGS which carry them around gaily and happily or even grumpily but at least carry them. So you need to keep trying on characteristics that seem to chime in with the name and character's context, seem to mix into a potent cocktail that moves. For example I spent a long time building this character X who was supposed to be an expert on the jungle, knew about plants, etc etc...but it was all a bit static. No legs. Then I had a mid-morning coffee break insight that X was tough. That was it. I had my legs. I like writing about toughness and now I had my chance. So, it is likely that the key driving characteristic may be somthing simple that appeals to YOU, gets YOU a bit excited- or excited enough to want to write about it. One must always ignore what is 'good' or 'acceptable to the audience' at this stage- it's all about charging your own generative powers with whatever fuel they need.