"Sea lo que sea" and other similar structures

Question

As you know, there are standard rules for subjuntivo:

1. The sentence has to have two clauses.
2. When using verbs that impose their will, each clause has to have a different subject (verbs of emotion don't necessitate two subjects).
3. The verb in the first clause has to be a subjunctive indicator (there are words that can act as subjunctive indicators called "adverbial subordinators").

Example below is a classic structure then:

Espero que tengas un buen día.

But how the structures below are formed?

Sea lo que sea (Whatever it is)

Puedo verte donde quiera que vaya (I can see you everywhere I go / wherever I go)

Vayas adonde vayas (Wherever I go)

Lo que quiera que haga (Whatever I do)

Haga lo que haga (Whatever I do, similar to the example above)

Intuitively I understand the use of these phrases. It is just curious how these phrases are formed, which rules are used. These sentences seem to be made not in accordance with classic rules I wrote above, as they include 2 verbs in subjuntivo. Or I maybe am missing something.

Am I right that when you encounter such phrases, it is better to just understand what they mean and memorise these phrases as they are (like idioms), rather than analize the use of subjuntivo in such cases?

IMPORTANT: I also found the link with an answer regarding estructuras reduplicativas de subjuntivo ¿De qué tipo de tipo de oración subordinada son "Sea lo que sea", "fuera lo que fuera", "haga lo que haga"? But the answer there still doesn't explain the forming of 2 sentences (because there are no 2 same verbs, rather for some reason subjunctive form of querer is used):

Puedo verte donde quiera que vaya

Lo que quiera que haga

Answer 1

The reduplicated subjunctive

The answer you found is correct and, if you have understood it (as you seem to have done), it covers all the cases where the verb is reduplicated. It's just an idiomatic way of saying "whatever (the subject) does..." (for example: hagas lo que hagas = "whatever you do").

In the case of sea lo que sea this same structure is at work, only it's usually impersonal: sea lo que sea means "whatever it is" but that "it" (the implicit 3rd person) is not necessarily a referent; the phrase can mean just "in any case", or "whatever happens".

The -quiera words

The sentences not covered by the answer are those where you think you have found an extra verb, querer, in the subjunctive. This is in fact not so. The word dondequiera means "wherever". It's part of a little family of similar words including quienquiera "whoever", comoquiera "however" (="in whatever way") and cuandoquiera "whenever". (The RAE says it's also right if you write these as two words, e.g. donde quiera, but in most places you'll see that's not recommended.) These words come very transparently from the merger of a relative pronoun (donde, quien, como, cuando) with the third person singular, present tense, subjunctive mood of the verb querer, but they don't have anything to do with the idea of querer ("to want") anymore.

The -quiera words work in the same way as their equivalents in English.

• dondequiera que vaya = "wherever I go"
• quienquiera que diga eso = "whoever says that"

Note that there is no such equivalent for "whatever". That is, there is no word *quequiera (and your example Lo que quiera que haga is ungrammatical). The correct equivalent would be the phrase cualquier cosa (e.g. cualquier cosa que haga = "whatever I do").

-quiera plus subjunctive or indicative?

Although you've found examples where the -quiera words are followed by subjunctives, this is not always so. You can say

• dondequiera que voy
• quienquiera que dice eso

They mean almost the same, but when the verb is in the subjunctive, it denotes a hypothetical fact, while the indicative mood shows an actual fact. So a better translation would be

• dondequiera que voy = "wherever I go" (i.e. "I go to places and in every place something happens")
• dondequiera que vaya = "wherever I may happen to go" (i.e. "if I went anywhere I'm sure something would happen there")

In common usage

The -quiera words are not that commonly used in spoken Spanish. They're not exactly formal or literary but in informal registers they're often replaced by phrases of the same type as cualquier cosa que, i.e. instead of dondequiera que vaya people tend to say

• en cualquier lugar (a)donde instead of dondequiera que;
• cualquier persona que instead of quienquiera que;
• de cualquier manera en que instead of comoquiera que;
• en cualquier momento en que instead of cuandoquiera que.

Apart from that, comoquiera is rarely used, and cuandoquiera sounds positively archaic.

Answer 2

Notice you don't need the same verb to use this structure. Other constructions using different verbs would also call for the subjunctive. Consider the following extract from a book:

Haga frío o calor, llueva o haga sol, el ejercicio antes de una comida es bueno para la salud.

In this sentence, the subordinates "haga frío o calor" and "llueva o haga sol" can be thought of as subordinadas adverbiales concesivas, thus requiring the subjunctive. Subordinadas concesivas are subordinates that pose an obstacle to what is expressed in the main clause, while not completely preventing the action. The English equivalent would be clauses introduced by despite, regardless of, even though or albeit. If what is being expressed in the subordinate clause is hypothetical or unspecified, you need the subjunctive.

While most subordinadas adverbiales concesivas are introduced by aunque or a pesar de (que), you could rephrase the sentence above as:

Aunque haga frío, aunque llueva, el ejercicio antes de una comida es bueno para la salud.

Now it's easier to see why you would need the subjunctive there. Going back to the examples you've given, they can be thought of as subordinate phrases where the main sentence has been elided:

Vayas donde vayas, te encontraré.

Lo que quiera que haga, nada me sale bien.

Because both subordinate clauses are unspecific, they call for the subjunctive.

The phrase "donde quiera que vaya" is similar but a bit different in that it is a subordinada adverbial de lugar, that is, a subordinate that specifies a place. You can recognize a "subordinada de lugar" by swapping the subordinate with allí or en ese sitio:

Puedo verte donde quiera que vaya -> Puedo verte allí. / Puedo verte en esos sitios.

If such place is vague or unspecified, as is the case with "donde quiera que vaya", you need the subjunctive.

I hope I've made the grammar a bit clearer. It might be just easier to remember that you need the subjunctive because the prases "wherever" or "whatever" introduce a sense of vagueness that fits the subjunctive mode better than the indicative mode.