I don't have a lot of war-suited characters, so a lot of these guys will have motives besides hunting the monster itself. They'll still get dragged into the hunt one way or another though, not to worry.
Erasmus is a vampire. Specifically, he's a Thorn, a hunter of his own kind, responsible for hunting down accidentally-turned vampires and those members of his court that break its laws. At this point in time, however, an attack on his court has left most dead and the survivors scattered, and in the ensuing chaos, his twin sister has gone missing. Erasmus has reason to believe she might have ended up involved in the war somehow, and is setting out in search for her. Decades of servitude and vampiric politics have left him cold and pragmatic. He likely joins the monster hunt investigations to provide cover for his real purposes, or to gain greater access to more areas.
Xavi is a member of the Sentinels, an order of demon hunters from outside Evelon. He's rather irate to find himself here; not only is this realm outside their usual jurisdiction, Xavi himself isn't even a field agent, but an archivist. However, he's been ordered to investigate evidence of demon activities in these parts, and it just so happens that the reports of the attacks started up just as he arrived. He is emphatically not suited for combat, and hopes to find information either from a safe distance from the action or with the aid of someone more fighting-oriented. It's best not to mention his outward age; he's been a 'young boy' for centuries now, and is getting mighty tired of hearing about it.
Esmond and Larkin are wandering adventurers who get dragged into all kinds of stuff. Monster hunts, putting someone's soul to rest, getting the old man's cat down from the tree, anything goes for them, really. They can be RPed either together or separately (though Esmond is easier for me to write than Larkin). Ezzy's main specialty is healing, though he's picked up a few offensive spells here and there in his travels. Larkin's skills lie mainly in pickpocketing or a knife through someone's ribs in the dark. He's in it to help people, while she's mostly thinking of getting paid.
In a similar vein to Erasmus, Kenric is looking for his lost protege, a young boy named Dante. He had originally come to the war to serve as a medic, and he has some prior experience with field duty thanks to his stint in a smaller civil war in his homeland. While he would like to search for his charge, the armies at large seem to find the monster a higher priority... And there's a chance that the creature could kill Dante too, as long as it remains at large. Still, considering his skillset, he'd fare much better if matched with someone with more experience tracking down murderous beasts.