Are Mass intentions always efficacious?

[Daniel]

Suppose a priest offers a Mass on behalf of someone to whom Jesus does not want to give grace.

What happens?

Does Jesus pray on behalf of that person even against His own will?

Does Jesus pray on behalf of that person, but only for natural benefits rather than for grace? (So that the beneficiary does not receive grace but might nevertheless become rich or famous.)

Does Jesus simply ignore the priest's request, and not pray on behalf of that person? (Is that Mass more or less wasted, or are the graces applied elsewhere?)

Can this bring a curse upon the priest or upon the person for whom it was offered, for having attempted to offer a Mass contrary to God's will?

[christianchannel]

yes always.

[Non Nobis]

Suppose a priest offers a Mass on behalf of someone to whom Jesus does not want to give grace.

What happens?

Does Jesus pray on behalf of that person even against His own will?

We can pray to Jesus to intercede with the Father for someone (ask Him to pray) but since He is God we can also ask Him to act directly (Jesus grant me grace to fulfill Your will more perfectly).   I don't know what words priests would use.

I think the fact that a priest is offering a Mass for someone only comes about because Jesus wills to give him grace.  But a person can reject sufficient grace by his own fault.