Questions & Answers about Hätte ich hier hupen oder bremsen sollen?
Why is it "sollen" at the end instead of the past participle "gesollt"?
When a modal verb like sollen is used with another verb in the perfect tense, German uses the double infinitive rule. Instead of using the past participle gesollt, you just use the infinitive sollen right after the other infinitives (hupen oder bremsen).
How exactly do you form "should have done something" in German?
You use the Konjunktiv II (subjunctive) form of haben, which is hätte, plus the infinitive of your action verb, plus the infinitive sollen. So, "I should have honked" literally translates to "I would-have honk should" (Ich hätte hupen sollen).
Why are there three verbs stacked at the end (hupen, bremsen, sollen)?
Because all infinitives get pushed to the end of the clause. Here we have two action verbs connected by oder (hupen oder bremsen) followed by the modal verb sollen. The modal verb always comes last in this double infinitive structure.
Could I just ask "Sollte ich hier hupen oder bremsen?" instead?
Sollte ich usually means "Should I?" (present/future) or "Was I supposed to?" (simple past). To express a missed opportunity in the past ("Should I have done that?"), you specifically need the hätte ... sollen structure.