The emphasis of using the volitional form

Question

I've come across this sentence:

脅かそうとしてたのか？

First, I'd like to verify that おどかそう here is the volitional form and not something like そう.

If that is indeed the case, then I've been wondering how the sentence would change (if at all) if it used 脅かす instead of 脅かそう.

For context (Spoilers for それでも歩は寄せてくる chapter 39):

How does the emphasis or nuances of the sentence change if it was written as:

脅かすとしてたのか？

Answer 1

脅かそう is indeed the volitional form of 脅かす. If "to try/attempt to surprise (me)" is the intended meaning, you must use a volitional form before とする. Always.

• JLPT N3 Grammar ようとする (you to suru)

脅かすとする is totally different. It's an uncommon, colloquial version of 脅かすことにする meaning "to decide to surprise". For this usage, see: What does verb+とする mean? This pattern is seldom used in the past tense, and "Was this because she had already made a decision to surprise me?" makes no sense in this context, anyway.