Sticky, nsfw, Soundwave/Megatron with Soundwave/Orion/Megatron implied.
After the arena, before the revolution, Soundwave curled himself into Megatronus’ heavy heated plating and let himself rest.
He’d detached his deployers, made himself small so he could better fit into Megatronus’ embrace. There was no need, at the moment, for the bluff and bluster of the arena: Soundwave was an equal part of their whole, if a happily subordinate one.
He opened his body for Megatronus, let him take, and take, and take, until the huge body lay exhausted on top of him. The spike nestled still stubbornly inside Soundwave, sending slow pulses of current through Soundwave’s sore channel.
In return, Megatronus opened his processors. Soundwave’s cables wrapped around and around him, plugged into sockets accustomed to his use. Megatronus’ restless power, and rage, and betrayal washed through Soundwave’s processors, and Soundwave held him faithfully and believed in him utterly.
The two of them were one, and they almost forgot that there should have been three.