I would consider Jack as an ENFP (aka campaigner personality type) and Ennis possibly a ISFJ which is the defender personality type. Ennis is a bit harder due to him being very reserved and emotionally closed off. I believe Ennis is quite damaged and not as emotionally resilient as Jack. Nothing matches perfectly of course, but assigning them personality traits allows you to better understand how they might think and feel, and the potential for what they could be under different circumstances.