#dm suggestions

Ah you have a player who doesnt do encounters? well, theres a couple ways you can handle it, probably by weaving in a story element or character trait that explains why they take a backseat. A character with brittle bone disease who chooses not to fight but engage in social encounters instead perhaps, although do be mindful about how you or your players portray real world diseases. A fantasy alternative may be more appropriate.

A character whose bloodline is cursed with a type of lycanthropy where if their heart-rate raises above a certain point they start to turn into a monster, so its on them to constantly monitor that and proposes an interesting challenge to your players, like  ‘be careful on this hike, lighten their load a little bit they are starting to sweat, how you doing pal? ‘. Maybe once or twice on a constitution saving throw when the you think “I dunno you were getting pretty upset, roll for it” they actually DO turn into a monster, and your other players have to subdue them without hurting them, or the monster goes on a rampage that the DM controls. 

A character whose hyper sensitive to the sounds of clashing metal and has to keep a distance but provides valuable support in other ways. 

A character with a curse that states if they ever drawn blood in another the same wound will appear on their own body, this curse cannot be broken within their lifetime, but perhaps they quest to free their children from it. This could come up in an interesting way if the character had a role like a surgeon, where they are forced to make these heart-pounding choices. Make the cut and feel it too, or we lose this guy. It would be an interesting consequence to natural 1′s for this player, if their mistakes lead to them accidentally hurting a party member, and they immediately start bleeding in the same place and revealing their circumstance to everyone else when it was previously a secret. 

The worst case of face-blindness anyone has ever had to deal with, and in the heat of the moment the player notoriously cannot sort out friend from foe and keeps taking swings at the wrong guys, so they’ve been permanently benched by their companions for safety reasons. 

I’m not sure if this is meant to be sarcastic or not, but it does sound like a fun idea. I looked up your catcroc (pakasuchus), and that would only be fair. As for a nation/setting of lizardfolk, is it just lizardfolk or are there Tortles and maybe some Pterasaurians in the population as well? Then there’s the standard world building stuff of terrain, politics, religion, and trade. For terrain, I’d personally go for a mix of grasslands, swamps, marshes, lakes, and a few hilly areas.