TRANSFORMERSG1Thundercracker x Soundwave
(I swear this is not a crack pairing its quite conman. Its based on a few moments Thundercracker seems to be fallowing Soundwave even one moment protecting him. On the Thundercracker Masterpiece figure there is a silhouette of him HOLDING Soundwave in his hand!)
Jetfire/Skyfire x Starscream
(In the series its said they were companions back on Cybertron and worked together. They seemed close until Skyfire dident like what the Decepticons stood for anymore and left making Starscream hate him.)
Skywarp x Thundercracker
(I got nothing besides they work together and look good.)
Megatron x Starscream
(Though they seem to just hate and somewhat tolerate one another I like to think Starscream honestly needs Megatron. Maybe even admires him because he is a ruthless and powerful leader. Though he seems to think he could do better there is a seance of self doubt in his ability when given the chance, shown in the comics. Also this somewhat proves it its the ending to All Hail Megatron.
Spoiler