So Sarah's housewarming party isn't far off. Megatron and Prime are working hard to get it organized (right?). Megatron is the king of delegation, so he finds himself a pair of idle hands and puts them to work...but goes along to 'supervise'.
That's how Megatron and Alexis
end up in a Walmart somewhere inside the city.
This won't end well, as Prime would say.