____ and he?

If you want to see if the sentence makes sense, just take out the words "and" and "Ariel."

So if the sentence is, for example, "He and Ariel have funny names," then you'd get "He has funny names."

If you have "The cold is bad for Ariel and he," then you get "The cold is bad for he." This sounds wrong, and it certainly is wrong.

Simplest way to see if it's right.

I don't know if this is a rule or not, but if it were the subject of the sentence, I would use "he and Ariel...", not "Ariel and he...", that is, I would not try to parallel the "I comes last" rule. The reason I would do it this way, is "he" is singular and "he and Ariel" is now plural. If "he" comes after "Ariel" then you would have the singular "he" followed by the plural form of the verb. Now, this would not be incorrect gramar, but it might be awkward to say: Ariel and he have funny names. The "... he have..." might sound strange even if correct.

Taking out the 'and Ariel' part has always been my general rule for this sort of thing; it's the easiest way to determine whether or not the names and pronouns are in the proper order.

Also, remember that the "____ and I" construction is not a *rule*, but a *courtesy*, implying that the other persons listed are being given a certain level of respect.

*Is* it just a courtesy? "That idiot and I are going to come to blows" sounds more natural to me than "I and that idiot are going to come to blows," and there's certainly nothing Miss Manners-approved about either version.

It seems to me that "he" or "him" would depend on where he and Ariel appear in the sentence diagram.
"Ariel and he" or "he and Ariel" as the subject
"Ariel and him" as the object

As far as the "'I' comes last" rule is concerned, I have always understood it to be a rule and not just a courtesy.