The relative pronoun agrees with the antecedent in number and degree of animacy (all animates use the epicene gender). The relative pronouns are identical to the subject forms of the corresponding third person personal pronouns.
The relative pronoun occupies the subject slot of the subordinate clause. If the pronoun has object function, it is resumed in the object slot with le.
When an impersonal construction occurs in a relative clause, only one lea is used when two would occur adjacently: salea lea furat Ayrean "someone who is called Ayran" instead of *salea lea lea furat Ayrean.
The pronoun le is used in any situation where the subject of the main clause needs to be referred back to, either in the main clause itself (usually reflexive: the object is the same as the subject) or in a subordinate clause, especially when the subject of the main clause is the object of the subordinate clause.
An example from the Charter of the Guild of Anshen:
Semte rastinan dilat alea cul gifted-nom-s intelligent-acc-cp do-PRS-3s all-O how
le dilayt puret RES do-PRS-3p wish-IRR-3s
"A gifted person treats all thinking beings as he would like them to treat him"
The le in the subordinate clause is the object of dilayt "they treat" and refers back to the subject of the main clause, semte.
The resumptive pronoun le is also used for the reflexive. It has the same form for singular and plural: le grelat "he shaves", le grelayt "they shave". Obviously, if it's not the subject who is shaved, the same verb can be used non-reflexively: lei grelat "he/she shaves him".
Many reflexive verbs have a separate meaning: rada "to swear", le rada "to decide (on something)", "to make up one's mind".
Some reflexive verbs can have a direct object: le tisa le rada "to decide to serve oneself", Arin sayali le burat "Arin asks himself all kinds of things".
In most southern dialects the first and second person have their own reflexive pronouns: ne grelan "I shave", te grelay "you shave". In the dual and plural, Essle has le in all persons, whereas Ryshas has ine, ane for first person and ite, ate for second person (but still le for third person).
For added emphasis the third person uses gendered pronouns with -arne "self" suffixed: learne "himself, him/herself", lyarne "herself" and theoretically (since arne tends to refer only to animates) liarne "itself". The reflexive pronoun is still required: learne le grelat "he shaves himself". For first and second person, the expected *iyarne and *tiarne don't exist, not even in dialects with separate first- and second-person reflexive pronouns. Instead, plain arne is used: arne le grelan "I shave myself".
In the plural, some dialects have (-)arne and others (-)arni: arne le grelayn or arni le grelayn "we shave ourselves", learne le grelayt or learni le grelayt "they shave themselves". Though le is an object form, arne and arni keep their original nominative ending even if the subject is explicitly mentioned: Arin so Jeran learni le grelayt "Arin and Jeran shave themselves".