Alvin was extremely perceptive about social cues. The moment Frigga finished speaking, he had a suspicion...
Seeing Frigga hesitate, Alvin thought for a moment, then asked, "Did one of Thor's friends from Vanaheim come to Earth too?"
Frigga nodded. Alvin had put his finger on the key point. "Yes. Asgard once had the famous Warriors Three.
"Volstagg, the Dwarf prince; Hogun, the Asgardian general; and Fandral, the prince of Vanaheim.
"They were always at Thor and Loki's side when they were young. Along with Sif, the six of them formed a little group and spent their time playing and fighting together...
"But in the end, Fandral chose to return to Vanaheim, and eventually he came to Earth too."
Alvin frowned and glanced at Thor. He had met this so-called Fandral, and had seen Hogun lose an arm during the battle over the throne of Nidavellir. He had also crossed paths with Volstagg quite a few times.
Volstagg and Fandral were "hostages" sent to Asgard by powerful realms within the Nine Realms. Their rulers hoped the two would influence the future king of Asgard.
In the end, they had failed, since the new king had turned out to be neither Thor nor Loki. But that didn't seem to have affected their friendship with Thor.
The first time Thor came to Earth, they had all appeared in New Mexico and protected him as he fought Loki.
Now Alvin understood what Frigga had wanted to tell him.
Thor himself wasn't actually willing to leave. After all, there were two pretty girls on Earth who were always orbiting him, and the Thunder God wasn't exactly ambitious.
He was choosing to leave only because he didn't want everyone caught in the middle when Alvin chopped Fandral up.
Thor was a loyal man, but he understood