Disclaimer: The usual.
If Glorfindel had wanted to be shoved into a closet, in his bathrobe, he would have asked. Since when did Elf-lords of such calibre manage to fall prey to Elves of not-so-much-calibre? He examined the space that he had been allowed and reluctantly admitted the twins' good taste in closets.
But that still does not excuse this, he thought, just fantazising when he would finally be able to punish them with five months of cleaning the horse stables. With one fork. Despite the current situation, his mouth curled into a grin.
Then Glorfindel grimaced as his wet hair touched the wall. If he hadn't allowed himself to be goaded into this...
"Glorfindel!" called one voice.
"Glorfindel!" called another.
Oh, Blessed Ones...why me...?
"Do you think he's ignoring us?"
"I don't think so. Let's try again—GLORFINDEL!"
Glorfindel had unwittingly followed, thinking that this was some urgent matter, but apparently he had been mistaken. If they were vandalising his room, they would never live to see thirty summers. Honestly, where had he gone wrong with them? Wasn't he the one that told the twins not to play pranks on him because it wasn't plausible (he died once, he didn't want to go back by suicide)? Didn't he precisely tell them that they could play pranks on Erestor instead? Or Gil-galad? Or Melpomaen? Or Lindir? Or their parents?
He knocked on the door—from the inside, ironically—and waited for a reaction. When there was no response, he placed his ear a thumb's length away from the door (Elven ears are sensitive) and tried to listen for footsteps.
As was his luck, there were no such footsteps.
So Glorfindel, being the smart Elf he was (keyword was; after all, he did walk outside of his room clad in pants and a bathrobe only), tried to pick the lock with an unidentified object. Then, sticking the thing through the keyhole, he twisted the knob and wrenched the door open forcefully for good measure...
...to find that the door wasn't actually locked, and he basically wasted time that could have been spent throttling Elladan and Elrohir on trying to unlock an unlocked door.
Sighing, Glorfindel got out of the closet easily enough and walked stiffly down the hallway, and down several other hallways, until he reached the main hall. Upon arrival, he received many skeptical glances. Only Lindir, who meandered by, greeted him, thankfully not mentioning his clothes...or his lack of it.
He nonchalantly told Glorfindel that Elrond wanted to see him in his study, and that he was going to be late by two minutes if he did not hurry up and hightail it out of there.
Glorfindel was not in a good mood. He made a point to walk slowly to Elrond's study, greeting every single Elf, Hobbit, Dwarf, and Man that walked down the hallway, purposely examining things that he always ignored. If Elrond was going to tell him off for being late, Glorfindel didn't care.
He calmly opened the door, turning the knob at a pace that was the exact opposite of Oropher's temper. Then he stepped inside, carefully staring at the walls and then the large banner that adorned the west wall and the left, and then the—wait, what?
"Happy conception day, Glorfindel!" the group underneath the banner chorused.
Well, that just blatantly ruined Glorfindel's plans of stringing up the twins into their mother's gowns, but it explained the twins' hastiness to get away from the closet. He found that he couldn't be angry at them, and so many faces were expectant for his smile.
So he enlightened them with an upward quirk of the mouth.
Towards the end of the birthday party, Glorfindel had gotten his revenge.
Until...
"Say, Glor, why are you clad only in a bathrobe?" Elrond asked.
Don't worry; Glorfindel was very happy.