if i play fizz trickster and play a star crossed can it target the same fizz

Yes — Star-Crossed can target Fizz, but only as the "friendly unit." The other half of the spell ("an enemy unit") must be a separate unit; a single unit can't be both friendly and enemy to you (Rule 355.9.b).

The spell played via Fizz is a separate game object from Fizz's ability, so it can legally target him — same as any spell targeting its own source's controller's units (Rule 355.9.c; FAQ #9320). Since Star-Crossed has Energy 3, it also fits Fizz's cost restriction (≤3 Energy, ignoring its Energy cost, still paying its 1 Power).

In short: Fizz + one enemy unit, both to their owners' hands, then Star-Crossed is recycled.