Correspondence with developer:

Q: How does Charles Ross, Esq. work? The card doesn't explicitly states its time window. Can you use its ability then in the next round use up the cost reduction? Maybe even use it twice before playing an item? It using at your location, does it mean your location when you use the ability, or when you play the item (if you use the ability and then move, where can you play an item at reduced cost)?

A: Correct; Charles Ross’s ability applies until it is used, so if you use it in one round you will still get the discount next round, and if you use him more than once before playing a card, you would get a –2 discount. As for your second question, if you move after using Charles Ross’s ability, the discount would apply to the next Item asset played by an investigator at your new location, not the former location.

So basically you can get one additional resource from it per round. Awesome for a 2 resource card!

The discount build-up feature ( once per turn without playing any Item yet) works well when you are playing with firearm-based teammate. While the fighter is using the ammo of their current gun, at the same time you save up the discount for the fighter's next gun, possibly reduced to 0 if enough turns passed. Sometimes when I use Dr. Milan Christopher and continue to get +1 resource every turn yet it cannot help the fighter take the heat off me, I think Charles Ross, Esq. is a great alternative.

I see good synergy with Bob Jenkins. Somebody else plays Bob who then plays your items (or somebody elses) and Charles pays for the stuff.

Take him yourself using 1 / 2 Versatile do get some other class items and more rogue-zeros. Or let somebody else take Charles Ross, Esq..

Now, how does this work on Lola? If she is not in seeker role, would the discounts built up prior still usable/apply later? Or does it only apply on seeker/neutral items when she is a seeker?

Stretching it further, what if Ross is defeated/replaced (on Lola, or any investigator)? Would the discount built up still apply? Likely not, but if it does it would be really good, especially for Lola whose Ross easily dies to COI.