"Pronominal verbs" (along with others that behave in a similar fashion) make up a large and relatively complex topic, so I'll just get into some very simple aspects.
These verbs can be recognized because the infinitive always ends in "-se," and they are always conjugated with the clitic pronouns: me, te, se, nos, os/se, se:
- yo me arrepiento
- tú te arrepientes
- ella se arrepiente
- nosotros nos arrepentimos
- vosotros os arrepentís/ustedes se arrepienten
- ellos se arrepienten
Truly pronominal verbs, like "arrepentirse" (to regret) or "atreverse" (to dare), do not have a non-pronominal form: neither the verb "arrepentir" nor "atrever" exist. However, many regular verbs have a corresponding pronominal form, for example, both verbs, "ahogar" & "ahogarse" (to drown) exist. From the point of view regarding direct and indirect complements, pronominal verbs are intransitive because they do not accept a direct complement.
Along with pronominal verbs (both pronominal and strictly pronominal), there are others that look and are conjugated the same, but serve a different purpose: reflexive, reciprocal and dative. All these pronominal-like verbs derive from regular verbs, so the verb "vestirse" comes from the verb "vestir". These pronominal-like verbs maybe be used transitively or intransitively.
The following list briefly describes each type of verb.
- Reflexive verbs: used when the action is done to oneself, for example "bañarse" (to take a shower). These verbs are transitive and can have an indirect complement.
- Reciprocal verbs: used when the action is done reciprocally between two or more individual, for example "besarse" (to kiss). These verbs are transitive and can have an indirect complement.
- Dative (or emphatic) verbs: used to denote a more personal level of involvement, for example "beberse" (to drink).
- Pronominal verbs: a special kind of verbs; they may seem to denote a reflexive action, but they actually do not, for example "ahogarse" (to drown). These verbs are intransitive. Like the previous ones, these verbs have a non-pronominal corresponding form, for example "ahogar" (to drown).
- Truly pronominal verbs: a special kind of verbs; they could also seem to denote a reflexive action, but they do not, for example, "fugarse" (to escape). These verbs are intransitive.
So, regarding the sentences of this thread:
- Bea y Lin se están registrando en un hotel muy bonito. The verb "registrarse" is a pronominal verb, as Bea and Lin are not "registering themselves,"
- Lin señala un ratón que se está comiendo la galleta. The verb "comerse" is a dative verb, as the mouse is not eating itself.
The following answer talks a little about the emphatic verb:
el perro nos come las plantas
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Just in case someone misses the referred link about the possessive or sympathetic dative mentioned at the previous thread:
"dativo posesivo/simpatético".
ㆍespañol ㆍgramática