TIME FOR AFTERCARE.
Oh, but wait! You two didn't negotiate aftercare! You didn't realize it was necessary! Well, that's ok. See, unlike the scene the two of you just hashed out, aftercare has nothing to do with what she wants. Hell, she doesn't know what she wants anymore. Look at her; her eyeballs are rolling around her head like a pair of googly-eyes on a cookie monster doll. It's up to you now to know what she needs. Be the Top! Treat her the way she needs to be treated! She may not thank you now, but she'll be grateful in the long run, believe me.
(And I must know what I'm talking about, cause I'm taking the time to write a whole fucking post on aftercare, and these posts are always chock full of awesome goodness, aren't they?)
1. Set her down somewhere in a dark, quiet corner to relax. It should be dark enough that she can fall asleep if she wants to. Hell, it should be dark enough she can't see one foot in front of the other, cause why should she? It's not like she's going anywhere. In fact, it might be a good idea to put some legos on the floor, so you know if tries to get up and walk around; her hollers will warn you in a hurry, so you can put her right back where she belongs. If her friends think it's weird you're hiding her away where nobody can see her, snub your noses at them. This is aftercare, baby.
2. Make sure she has a nice, cozy blanket around her. Her arms should be good and snug by her sides, so she can't flail them around and accidentally hurt herself. Remember, she's got about as much sense now as a newborn babe; in her state, she might do some real damage to her face. In fact, it might be a good idea to go ahead and get out the nail clippers--blunt those nails down. Now's not the time to worry about her manicure. THIS IS HER SAFETY WE'RE TALKING ABOUT.
If you don't have a blanket, a straitjacket will do. The important thing is to make her feel secure, protected, and cared for. As you're fastening the straitjacket, you can whisper sweet words in her ear about how she's not going anywhere, and you've got her under your complete control. Let her feel the love.
3. Put some cream on those bruises. Arnica cream is awesome for this; petals from the Calendula Officinalis plant are good, too, and what's better, you can make a tea out of them! Just stick a funnel in her mouth and pour it down her throat. Remember, she needs to be rehydrated, and it's your job to see to her needs!
As you're applying the cream to her skin, rub it in like you're preparing a nice, juicy steak for the grill. It might hurt her, but hey, that's what S and M are all about. While you're rubbing, you can sing a little song to lighten the mood, like "It rubs the lotion on Its skin." The funny looks she'll give you will be those of admiration and respect.
If some of her skin has been cut, take heed: you don't want those cuts to get infected! It's time to pour on the alcohol. She'll scream with pleasure.
4. Give her some food. Have some ready, whatever you think you'll be in the mood for, since you know you'll be noshing on it, too, and she won't really care anyway. Don't worry now about any allergies she might suffer from; the important thing is to get her energy levels and endorphins back up. Chocolate is the best thing for this. If she refuses to eat the chocolate (for some stupid reason like she's on a diet or it has peanuts), pretend like you're in the Harry Potter universe and she's just been attacked by Dementors: GET THAT CHOCOLATE IN HER BELLEH. It's for her own good. If she continues to balk, pretend like you're a real wizard, get your wand out, and start yelling expecto patronum! around the room. A little cosplay never hurt anybody.
5. Give her time. Again, she's not going anywhere until you decide she's safe and ready to go. It could be hours; it could be minutes, if your ride's waiting for you and they've already got the engine idling. The important thing is to make sure she gets to her next destination safely. If you can't do this, ask a couple of your friends to watch over her. It doesn't matter if she knows them or not; she needs to trust in you now, to make the best decisions for her. And those "friends" you just made at the bar, who are eyeing her like she's fresh-baked bread? They will take awesome care of her while you move on to your next scene. (No, you don't need their last names or phone numbers, and it's impolite of you to ask. Confidentiality is key here.)
6. Check in on her the next day to make sure she's ok. If she doesn't accept your phone calls, keep trying; she might just be processing the lovely scene you two shared. If she starts yelling and screaming at you over the phone to leave her the fuck alone, don't take it personally--she's just going through subdrop. In fact, if she is going through subdrop, it might be a good idea to show up at her place unannounced just to let her know how pleased you are with her and how you'd love to play with her again sometime...like, maybe, right now? Don't take it personally if she calls the cops. Again, this is normal subdrop behavior. She'll get over it, and once she does, she'll be fine, ready, and raring to go!
So there you have it. A guide to aftercare. Remember, it's all up to you now.
She's bloody and loopy, but don't despair! She just needs some aftercare!
(*In all seriousness, I do not understand why so few couples negotiate aftercare before they start a heavy scene. But if this happens to you, the most important thing is to follow the bottom's cues, do whatever is right for her/him, and don't blindly follow any piece of advice you read in a BDSM post just because it was written by some "expert." You didn't play with the "expert," you played with the bottom in front of you. Their wishes, and their safety, is most important.)