Out of luck?
Our story starts on the seventh floor corridor just outside the Room of Requirement. House Elf Kreacher has been spying on Draco with Dobby for his master Harry. After being left alone by the caretaker Argus once before, he's been walking on a tightrope trying to avoid being detected by him and his pet cat Mrs. Norris again. His master prefers listening to Dobby's reports over his and he has ran out of luck... or so he thinks.
Kreacher said to himself, "The Malfoy boy stays in there for hours on end, what could he possibly be doing?"
After checking the coast was clear, he stepped out from his hiding spot and approached the wall where the door should appear.
Nothing happened.
Kreacher kicked the wall and winced slightly in pain.
A voice growled right by his ear. "Stop kicking that wall."
Kreacher jumped slightly and turned around to come eye to eye with Argus, Mrs Norris was at his heels.
Kreacher hung his head. "Sorry," he muttered."
Argus reassured him, "There's absolutely no need for you to apologise."
Kreacher told him, "I'm just frustrated, that's all. My master hasn't voiced it aloud, but I just know that he believes Dobby is doing his job better than me."
Argus glanced around and asked, "So, where is this Dobby now then?"
Kreacher replied, "He's either reporting to my master without me or he has managed to sneak into this room again."
Argus glanced at the wall and stated, "This room caused a lot of problems last year, but I got into it eventually"
Kreacher's eyes widened and he gasped. "How?"
Argus shrugged. "A student told me how to get in, but she said that you can only get in if you know exactly what it's being used for."
Kreacher sighed. "Well, that's useless."
Argus patted him on the shoulder and responded, "Hang in there, little guy. You have got this."
Kreacher smirked slightly. "Who are you calling little guy?"
Argus laughed. "Hey, it made you smile. That's what I was aiming for."