Rire is a true TEF deer; his appearance is exactly as it is in the Forest. Any mask he wears is truly a mask over a humanoid face, and his set may change depending on whatever other deer cast on him - though he generally returns to his "default" set after he gets bored with whatever's on top. He may keep a mini spell handy and use it on a whim, and his mask and antlers change fairly frequently. The Argus pelt is his favorite, however, and he rarely deviates from it for more than a day. He has several favorite masks, and may switch between them depending on what sound he prefers at the moment. It's rare to see him without a mask at all, but it does happen from time to time. The face beneath is neither young nor old, and may even seem to shift between brightly childish and quite mature or serious.

Rire never quite grew up. The memories of his fawnhood are bright in his mind, so he has a special spot in his heart for the little guys. Rire will often choose to cast spells on a fawn before a stag. Just because their magic doesn't last doesn't mean they can't play like everyone else, after all. He also tends to find himself in the company of fawns as often as or more often than he finds himself among deer his own age.
Rire also loves flowers - especially the purple ones! He likes having his favorite antlers, though, so he doesn't wear flowers often any more. The hollow full of blue flowers is a favorite sleeping spot.
He is more pacifistic than not, and chooses to ignore or back away from any challenges thrown his way - though that's not to say he wouldn't step up to defend a friend. He has also been known to step between combatants when they draw apart, and to push against his friends to discourage them from re-entering the fray. Although he will generally use his antlers against them in this case, he would never intentionally do damage with them.
The young stag can also be quite mischievous; he has been known to find sleeping friends and change their sets to match his own or someone else's. He also thinks spell fly-bys are hillarious, and will often get rid of an extra spell by speeding through the forest and casting it upon the first deer he sees, without stopping to even see who his victim was. All of his little jokes are well-intentioned play, however, and overall are rather harmless (although sometimes a lot of sneezing is involved in undoing his work). Even when acting serious, it's not long before he can be caught laughing again. The buck simply doesn't have it in him to be dramatic for any remarkable length of time.
That said, Rire is more often than not very quiet and quite shy and a little socially awkward in one-on-one situations, although he usually handles larger groups alright (since the focus is usually off of him). Many days he takes to sprinting through the Forest at random (because it's awful fun!), only pausing long enough to circle and leap around those he knows or often sees (a weird way to say 'hello,' but it suits him just fine) or who he thinks could use a bit of randomness, before he's off again and bounding over the terrain. Although he's been around for a while (off and on), he doesn't know many deer very well, though he knows a handfull of names on sight and may greet them at least briefly if he knows who they are.
Rire's recent activity is helping to change this, however; he is finding that he recognizes and is friendly with more and more deer.

Cadaver - Attacked a mini
Dinah Moon - Fighting too near a fawn. Reconsidering her, currently.
Gustiro - Won't let Rire near some friends. Curious of.
Tieff - Gustiro's helper

Most of Rire's actions are self-explanitory, but it never hurts to have a reference~
Please note that these are the most common explanations for Rire's body language. They are not the only explanations.

Stopping suddenly: Usually when Rire stops dead (in the middle of running, jumping, playing, spellcasting etc), one of my cats has jumped in my face or I am tinkering with a setting on my computer/adjusting the camera angle because I can't see through the trees. If he sits down suddenly, I'm probably adjusting something on the menu screen so that I don't lag/etc. Don't worry, he'll be back to normal in a minute.

Leaving without a farewell: Assume Rire will be back within 5 minutes. My game probably glitched and I had to restart to fix it - or one of my cats shut off the computer (which happens way more often than it should). Even if I'm in a hurry, Rire will usually say farewell before he leaves for an extended period of time.

Running/Leaping: Rire is happy and excited. If he's running in circles around someone, he's probably glad to see them.

Walk/Hop: Happy and excited, but not as crazily so.

Half-bow: Rire very rarely does a full bow. Instead, he'll usually half-bow and tilt his head to the side in a little nod. This is to be taken as a greeting and/or an expression of familiarity.

Full bow: The full bow is usually reserved for farewells (in which case he'll double bow - see below), for deer Rire recognizes as older than himself, or for deer Rire is especially fond of.

Farewell: Rire will often perk up/listen - "I think someone's calling me..." and then sad emote - "Oh, I have to go." Then he'll full bow twice and maybe attempt to nuzzle, if he's especially close to whatever deer are around, but this doesn't usually work very well (see below).

Nuzzling: Rire is not a very nuzzly deer. Part of this is because my nuzzle button doesn't work very well. If you see Rire regularly and consider him a good friend, but Rire flat out doesn't return a nuzzle, or sometimes will return a nuzzle and sometimes will back up and look stupid, don't be offended -- half the time the button just doesn't work right. :<

Listening/Turning: Rire thinks he hears/smells someone familiar, and is trying to hear/smell better. If he hops in the direction he stops turning at, he probably wants to go find whoever it is he's after, though often he'll stay with whoever he's been playing with out of courtesy.

Calling: Rire has lost track of whoever he was with, wants someone to join the group he's with, is startled, or is just messing around/happy.

Point/Nod: "Join us," or "Follow me!"

Point/Run: "Follow me!" - Rire will usually circle back a few times to make sure you're following before he runs off to wherever he has in mind. If you don't follow after a few moments, he may go off on his own.

Aggressive motions: Thus far, Rire has never displayed serious aggression except while defending other deer. Any lowering of antlers, rearing, or 'taunting' is shortly followed by either dancing or laughing, unless something has spooked him - in which case he may just run or back away. Rire hates conflict.

"Taunt": Rire usually uses this when he is anxious; it should generally be taken as a nervous prance, rather than a challenge. In general, the action is cut off about halfway through and Rire will pace in a nervous circle. May also be combined with the sad emote.