Originally Posted by Helped Wanted
Here, 'to' is optional. If a verb follows "dare" it does not need "to". In this way "dare" is functioning as a marginal modal verb.
No one dared say a word.
It is also correct to say, "No one dared to say a word."
If the base form of a verb follows "dare", an object cannot come between "dare" and the following verb.
wrong: No one dared him say a word.
Here is a very common phrase with "dare" that can be used by itself or with additional information.
"How dare you!" - The person that says this is not pleased with someone else and usually feels indignant to some degree.
"How dare you insult us. We do not find your comments amusing at all."
Without the "to" infinitive, the sentence somewhat more serious and formal.
The same thing holds true with "need not".
You need not say a word. I know exactly how you feel and what you are thinking.
This can also be, "You don't need to say a word. I know exactly what you're thinking."
We can also use "need" in an interrogative that has the verb and the subject inverted.
Need I say more?
Need you speak like that?
Do I need say more?
This particular usage of "need" is not very common and sounds very formal and serious. Be careful with it.