Another point of detail for understanding Vorthos is that it's not just a love for flavourful ideas on how to build your list, but also a sense of satisfaction from (may the powers that be forgive me for uttering these words) ludonarrative resonance.
As an example, there's the Vermin Swarm relic "Sceptre of Vermin Valour" which gives its wielder Stand Behind.
Just seeing a relic with that name and that ability tells you everything you need to know about the faction leaders, and keeps you from seeing the Safety in Numbers rule as a symbol of their ability to cooperate.
In general, I think the LABs of T9A handle this very well. They have a background driven design now and it shows. For example, the Favours of the WDG all capture the feel of the god pretty well. A warrior of Nukuja plays pretty much how you expect it to. One example can think of where we don't have this though are the Eidolons in the DL army. Their Dark Fire has a unique mechanic in how it interacts with armour, something that is really appealing to Melvin. However, in the fluff, the Dark Fire is described as something that tests the willpower of the target, causing some dissonance that annoys Vorthos. So some mechanic related to Discipline would feel like a better fit for him.