[Rusty]

In a subject / subject complement structure, the subject and the subject complement are identical (if the subject complement is a noun). If 'I' is the subject, what 'I' am is the subject complement, in other words. By the same token, if 'home' is the subject, what 'home' is is the subject complement. The subject always 'drives' your decision for verb conjugation.

The problem is, how do you determine who the subject is? Well, that very much depends on context and, in colloquial English, the subject is often listed first. For instance, it's perfectly fine to say, "The problem is you," where "problem" is the subject. If we switch the two nouns around, the linking verb becomes 'are', to match the subject 'you'.

The same logic cannot be applied in Spanish when the subject is a subject pronoun. No matter its location, the linking verb will always agree with the subject pronoun.

Mi felicidad eres tú.
Tú eres mi felicidad.

Soy el camarero.
El camarero soy yo.