I typically take alliances. Many times later on it is somebody about to get wiped out and looking for help, which I could not do in time anyway. I never trust my allies. Now, I guess if you get military access, those alliances are a lot more stable. I fully expect my allies to turn on me. I am surprised in my current Macedon campaign that Scythia has not yet attacked.

Only Romans are more untrustworthy than the Greek Cities
Truer words were never spoken. Britannia is bad about it as well. But after all, the Greeks are "those masters of lies, falsehood, and perversity", so I would fully expect them to break an alliance

I do not attack my own allies, except if I am Rome and ready to start the civil war. Or, as happened once, the Scipii attacked the Brutii, and the Senate ordered me to attack both factions, outlawing me if I did not hit the Scipii and investigating me if I did not attack the Brutii. I attacked both.

I never get anybody as a protectorate, either, except I had Egypt become a protectorate once when I was Macedon. Really annoying, I had all the map covered except for Egypt's settlements, they had I think seven left. But they were not violating it, so I left them be. I guess since they were my protectorate, technically I had the entire map conquered, or at least subjugated.