Questions & Answers about Не бойся, я помогу тебе.
Why do we use the imperfective verb бояться for "don't be afraid" when getting scared feels like a single, sudden event?
This is exactly what the current lesson is about! In Russian, negative commands (telling someone not to do something) almost always use the imperfective aspect. Even if you mean "don't get scared right now," the negative prohibition rule requires the imperfective form не бойся.
How is the imperative word бойся formed, and why does it end in -ся?
It comes from the reflexive verb бояться (to be afraid). To make the informal command, you take the command base бой- and add the reflexive ending. Because й counts as a consonant in Russian, we attach -ся. If the base had ended in a vowel, we would have used -сь.
In English we say "I will help", so why isn't there a future tense word like буду before помогу?
помогу is the perfective verb помочь (to help) conjugated in the present tense form. Because perfective verbs focus on a completed result, they cannot have a present tense. Conjugating them automatically creates the simple future tense. You only use a helper word like буду with imperfective verbs.
Why does the sentence use тебе instead of тебя for "you"?