Registering 2 domains at same domain registrar and linking between them safe?

Whats the risk if i register 2 domains at the same domain registrar and later interlink between them or redirect?

Same registrar is fine.

Use alternate hosts or Class C's (different pools).

i really doubt google is actively trying to track connections between sites just to penalize them.

if someone owns two sites, one whitehat and one blackhat, why would google punish both? but if both are blackhat, then yeah, that’s a more solid reason for google to hit them together