[sblock=on the care and feeding of dragons]
Haha, you guys are awesome.
With my judge hat on, the thing I want to avoid is having Sharpe (or anyone else) get a
permanent mechanical advantage that isn't balanced. A permanent draconic ally would certainly qualify; I wouldn't want to do that to Sharpe's next DM.
However, that leaves a lot of room to work with. There's a couple of ways we could go with this. First,
We could have the dragon for the this adventure, after that it could turn into a plot device or something for his (or everyone's) characters. Something a DM could pull out if he/she wanted too.
...this works for me. horticulture can have the dragon act as he sees fit for this adventure, including letting Sharpe run him in combat as an NPC if that's what you want, and we all agree that after the adventure we'll find a reason for him to go offstage. Sharpe can still talk about his dragon, even list him as an ally on his character sheet, but doesn't get to bring him along on future adventures.
Another thing we could do is award the dragon to Sharpe as treasure to use as a mount, using the mounted combat rules. That's balanced, because it wouldn't give Sharpe any extra actions (as it would if he had an npc ally a la 3.5e leadership feat), and any extra powers available would be "paid for" out of his treasure budget. We'd have to find an appropriate mount in the compendium to use as stats for him. Are there any low-level mounts with breath weapons? It wouldn't have to fly; we could just say that this dragon isn't big enough to carry a passenger in flight yet. If we can't find one with a breath weapon, we can just say that it can't / won't breathe on command. Maybe it injured its throat in this fight? I don't currently have DDI, and I'm at work, so I can't go poring through the mount lists at the moment. We can haggle about the details later, if this is interesting.
We could even do both: the dragon works as an ally for this adventure, but goes offstage at the end. Sharpe can later take the dragon as a mount by paying the appropriate amount. Depending on its stats, that might be many levels down the road.
Other ideas, now that you know roughly what I think is appropriate?
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