I just saw this question, which is about the whoever/whomever choice in these sentences:
I will kill whomever I despise.
I will kill whoever despises me.
It made me think; what is the object of the verb kill? Is it not who(m)ever? Then what is the object (subject) of the verb despise in the first (second) sentence?
And in general, is it possible that a word should have more than one grammatical function in a sentence? How?
Edit:
(This edit is a about the specific examples given above. If that's not an issue for you, just ignore it and read Greg's post, which answers the question in the title.)
Turned out my examples were not to the point. I Quote from A Student's Introduction to English grammar by Huddleston and Pullum, p.191:
Fused relatives
The final relative construction we consider in this chapter is the fused relative, illustrated in [19]:
- [19 i]: Whoever said that was trying to mislead you.
- [19 ii]: I 've eaten what you gave me.
This is a more complex construction than those dealt with above. Here the antecedent and the relativised element are fused together instead of being expressed separately as in simpler constructions. The underlined expressions here are thus NPs whose head is fused with the first element in the relative clause.
Whoever in [19 i] is simultaneously head of the NP and subject of the relative clause, and its gender indicates that we are talking about some person. The meaning is thus comparable to that of the non-fused
- The person who said that was trying to mislead you.
What in [19 ii] is likewise head of the NP and object of gave in the relative clause, and the non-personal gender gives a meaning like that of the non-fused (and more formal)
- I 've eaten that which you gave me.
So in I will kill whoever despises me, the object of kill is the whole relative clause (i.e., whoever despises me), and whoever is simultaneously the subject of despises and the head of the clause.
I'm not really comfortable with the idea of an NP whose head is a dependent of an element (here, the subject of a verb) inside that NP. It's a loop. There may be another way to describe this construction, so this loop could be avoided, but I'm going to leave it here for now.