Questions & Answers about Non ero sicuro che lei ce l'avesse con me.
How does the pronominal verb avercela break down in the phrase ce l'avesse?
Does the l' (from la) in ce l'avesse refer to a specific feminine noun?
Why is avesse in the subjunctive mood rather than the indicative?
The subjunctive is triggered by the main clause Non ero sicuro che (I wasn't sure that). Expressions of doubt, uncertainty, and personal feelings almost always require the subjunctive mood in the dependent clause that follows.
Why do we use the imperfect subjunctive (ce l'avesse) instead of the present subjunctive (ce l'abbia)?