The reason why Axel didn't want Elias to drop him off at the mansion was very simple and innocent, actually - he didn't want to implicate 'River' and force him to endure all the interrogation from his parents that would surely ensue. He had been missing since the evening before, and now he was returning home in such a… disorderly state, the Chandlers were bound to have multiple questions. River was a Beta male, so they wouldn't necessarily suspect that anything inappropriate happened, at least not anything sexual, and they certainly wouldn't insist on the two of them getting married (not that Axel would have minded… But he didn't want to scare River off. He had yet to even ask the Beta out on a single date!), but still.
Even if having another person with him could lessen the heat that Axel himself received, since his parents would be busy questioning River, Axel didn't want to put the Beta through it.
