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You might find that research isn't quite so important. If you're describing a banquet, you don't need to picture how the guests chew and swallow their food. For the scene with the two guys, you c...
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#3: Attribution notice added
Source: https://writers.stackexchange.com/a/38727 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#2: Initial revision
You might find that research isn't quite so important. If you're describing a banquet, you don't need to picture how the guests chew and swallow their food. For the scene with the two guys, you can focus on the foreplay - kissing, caressing, nibbling, petting, arousal, i.e all the things a person of either gender can imagine as pleasurable - and pay less attention to the genital stuff. If you feel compelled to describe the physical positions during coitus, it's also going to depend on how (a) experienced and (b) adventurous each character is. The mechanics are pretty simple: a guy comes by having his penis stimulated, usually involving friction - mouth, hand, anus, groin-to-groin, etc. The two guys can take turns, or they can stimulate each other simultaneously. But honestly, how they come is less interesting to the reader than how they each _feel_ and _behave_ - are they nervous? confident? over-eager? submissive? playful? dominating? clumsy? tender? overwhelmed? shouting "ride me cowboy"? For the guy in a wheelchair, sex may be more complicated. What's the nature of their disability? If it's a spinal injury, you'll need to address whether they can feel anything "down there". If they can't, there are special techniques to stimulate the penis to erection/ejaculation, but you'd have to research this - maybe the rehabilitation wing of a local hospital might be willing to help you. If the guy in the wheelchair can achieve an erection through the usual means, then it comes down to how restricted they are in adopting a desired position. Beyond that, see my comments in my second paragraph. I applaud you for the diversity of your characters, and not denying them the pleasure of physical contact. Most adult readers have experience of giving love and being loved; in the scenarios you've described, your task is to connect the reader with that experience. The mechanics are only relevant if they're _important in the story_.