Modal Verbs: Dare - Ought to

Dare

(Not usually used in the progressive tenses) to be brave enough to do sth: She said it as loudly as she dared. He didn't dare (to) say what he thought. They daren't ask for any more money. (Literary) She dared not breathe a word of it to anybody. There was something, dare I say it, a little unusual about him.
To persuade sb to do sth dangerous, difficult or embarrassing so that they can show that they are not afraid: [vn] Go on! Take it! I dare you. [Vn to INF] Some of the older boys had dared him to do it.

Idioms
Don't you dare! (Informal) used to tell sb strongly not to do sth: "I'll tell her about it. Don't you dare?" Don't you dare say anything to anybody?
How dare you, etc.: Used to show that you are angry about sth that sb has done: How dare you talk to me like that? How dare she imply that I was lying?
I dare say (also I daresay especially in BrE): Used when you are saying that sth is probable: I dare say you know about it already.

Grammar
Dare (sense 1) usually forms negatives and questions like an ordinary verb and is followed by an Infinitive with to. It is most common in the negative: I didn't dare to ask. He won't dare to break his promise. You told him? How did you dare? I hardly dared to hope she'd remember me. In positive sentences a phrase likes not be afraid is often used instead: She wasn't afraid (= she dared) to tell him the truth.
It can also be used like a modal verb especially in present tense negative forms in BrE, and is followed by an Infinitive without to: I daren't tell her the truth.
In spoken English, the forms of the ordinary verb are often used with an Infinitive without to: Don't you dare tell her what I said! I didn't dare look at him.

Ought to

Used to say what is the right thing to do: They ought to apologize. "Ought I to write to say thank you? Yes, I think you ought (to)." They ought to have apologized (= but they didn't). Such things ought not to be allowed. He oughtn't to have been driving so fast.
Used to say what you expect or would like to happen: Children ought to be able to read by the age of 7. Nurses ought to earn more.
Used to say what you advise or recommend: We ought to be leaving now. This is delicious. You ought to try some. You ought to have come to the meeting. It was interesting.
Used to say what has probably happened or is probably true: If he started out at nine, he ought to be here by now. That ought to be enough food for the four of us. Oughtn't the water to have boiled by now?