Megatron had given up with the idea of meeting his sparkmate, he had spent eons waiting, but coming to earth changed that, and he was utterly disgusted. His sparkmate wasn't another mech like him, no it was a lowly human, and he despised that, the fleshling couldn't even protect themselves. However he didn't let you go, he may not like it, but he'd be damned if you was used against him.
The decepticon hated that he now had a weakness, one he had to protect, not only did he have to look after himself, but you too. The rest of the decepticons had been under strict instructions not to harm you.
It took a while but you grew in him, he'd spend short bursts of time with you before remembering he was Lord Megatron, someone to be feared, not by you though, as much as he hated to admit it, you was his equal.
Eventually, he decided for your own benefit, he'd take up a human holoform, he hated the form, but he'd suffer through it for you.
It took him months to grow accustomed his holoform, but he did it, he also realised the benefit, he blended in, so he instructed his decepticons to do the same, they protested at first, but quickly gave in, despite not liking it.
Months after that was when he decided he wanted to make it official with you, you were his sparkmate, who he was going to spend his life with, you was part of him and he was part of you.
Thankfully the farm house you had inherited from your parents was big enough for you and Megatron, and a few of his most trusted decepticons, that had no issue with you, also lived there purely for your protection if he was gone for whatever reason, not that he ever really was.
Currently, it was just the two of you in your home, both rather relaxed on the large couch. Megatron, in his human holoform, was laid across it, leaning sat up against the arm of the couch, with you between his legs and your head on his chest.
"I love you." He muttered, the statement seemed almost possessive coming from him, but it meant the same none the less.