They follow the road because they want to, not because they must.
Sam had been a junior associate at Garrison for less than a week before its senior partner decided there was an additional function he wanted him to perform. Skeevy Alan Shore!Lucifer/baby lawyer!Sam, basically.
Super toppy alpha Lucifer does not like the fact that Sam has another alpha's scent all over him. Doesn't matter that it's Sam's brother's scent, Lucifer will not abide.