#maybe he was expecting a sonic who was immediately groveling and down to business

[cuchufletapl]

You know, I don't even think that Shadow was planning to punch Sonic flat first thing after meeting him again.

He's pissed, definitely wants to kick his ass and probably fantasized a hundred ways to strangle Sonic while floating in the void, but he's also spent whoever knows how long there trying to contact Sonic because he needs him to help him out of the void and knows they'll have to try to piece back their home together. When his glitched-out, hologram-looking message gets through to Sonic he doesn't sound particularly angry, it's more desperate, he's giving Sonic information so they can collaborate. He wants a team-up.

When he finally gets to him in person, he doesn't immediately launch into an attack, it's only when Sonic whines about wanting to get back home (a home that's been destroyed because of his recklessness) that Shadow is ticked off. That's when his demeanor becomes far more aggressive and he's like, "Actually. I'm gonna kill him first and then we'll see about saving our world."