(1) QUI + indicative: "qui-factual clauses"

QUI BONI SUNT, IDEM SUNT BEATI.   "Those who are good are also happy."

Note: When a clause like this is put into the subjunctive, the qui-clause becomes a 'dependent clause in indirect discourse', and thus it will require the subjunctive.

DIXIT EOSDEM ESSE BEATOS QUI BONI ESSENT.

(2) QUI + subjunctive: "qui-characteristic clauses"

Grammatically, these are a species of 'consecutive clauses', indicating the idea of 'consequence':

(a) after the demonstrative IS:

EA EST RAMANA GENS QUAE VICTA QUIESCERE NESCIAT.
" The Roman people is the sort which does not know how to be quiet after having been conquered."

(b) after NEMO, NIHIL, NULLUS, SOLUS, ULLUS, NULLUS, indicating 'existence':

NEMO EST QUI HAEC FACIAT. "There exists no one who would do this."

(c) after EST and SUNT: "there exists"

MULTA SENT QUAE MENTEM ACUANT. "There are many things which sharpen the mind."

(3) QUI + subjunctive: "qui-causal clauses":

A subjunctive after qui, quae, quod may be used as though the writer were thinking of cum ille/illa/illud + a subjunctive ('because': cum-causal); these too are a species of circumstantial clause, but are quite specific. There are in fact two kinds of qui-causal clauses:

(a) If the writer of the sentence is willing to vouch for the truth/accuracy of the reason ('because') in the qui-clause,
        he is authorized to use the indicative to indicate that the reason is a fact:

GRATIAM TIBI HABEO QUI VITAM MEAM SERVAVISTI (perfect indicative).
"I am grateful to you who (=because you) have saved my life."

(b) If the writer of the sentence is NOT willing to vouch for the truth or accuracy of the reason, then he will use the subjunctive to indicate the theoretical, or non-factual nature of the statement: (often with quippe, utpote, ut)

CAESAR, QUI PACEM CUM HOSTIBUS HABERE VELLET, LEGATOS LUTETIAM MISIT.
"Caesar, who wished [or so he said] to have peace with the enemy, sent negotiators to Lutetia."

ME MISERUM, QUI HAEC NON VIDERIM. (perfect subjunctive)
"Alas for me, who (=because I) have not seen these things."

(4) QUI + a consecutive clause which is used in the limiting sense:

NEMO (QUOD SCIAM)...
"Nobody, as far as I know,... "

(5) UBI and UNDE can also be used to introduce FINAL and CONSECUTIVE clauses in their capacity as relative adverbs:

MASSILIAM IIT UBI EXSULARET. "He went to Marseilles to live there in exile."

(6) QUI + a causal subjunctive clause (generally subjunctive):

ME MISERUM QUI HAEC NON VIDERIM! "Unfortunate me not to have seen this." "I am unfortunate
     because I did not see this."

But NOTE that if the writer wants to emphasize the actual reality of the idea of the qui-clause, the verb can be placed in the indicative.

GRATIAM TIBI HABEO QUI VITAM MEAM SERVAVISTI. "I am grateful to you because you did save my life."

Just as the concessive clauses are often indicated by a particle (TAMEN), so too qui-causal clauses have a characteristic set of particles (QUIPPE QUI, UTPOTE, UT):

EGO SEMPER PRO AMICO HABUI QUIPPE QUEM SCIREM MEI ESSE AMANTISSIMUM.
"I have always considered him as a friend whom I knew (= 'since I knew him' ) to be very friendly to me."

(7) QUI + a concessive subjunctuve clause (TAMEN).

(8) QUI + a circumstantial clause:

CAESAR, QUI HAEC OMNIA EXPLORATA HABERET, REDIRE STATUIT.
" When he had acquired full knowledge of all these things, Caesar decided to return. "

Compare: CAESAR, QUI HAEC OMNIA EXPLORATA HABERET, TAMEN REDIRE STATUIT.
"Though he had acquired full knowledge of all these things, nevertheless Caesar decided to return."