Rigel returned to Hogwarts by the same route, and as he approached the castle shore, he poked his head out of the water, briefly glancing around to confirm he was safe, then quickly emerged from the water, retaining his human form.
After drying himself with a spell, he calmly began to walk back to the castle.
It was almost dinnertime, so he didn't return to the Gryffindor tower, but went straight to the Great Hall, where, as expected, his friends were already.
Well, Harry and Ron were there, although the latter could hardly be considered a 'friend', Neville was probably still in the library at that hour, and Seamus and Dean might have been hanging out somewhere.
Along with the two of them, Hermione wasn't far away, pretending to write something, but Rigel could see from a distance that the girl was clearly paying attention to what they were saying.
Curious, he approached.
"...A three-headed dog! Seriously, what on earth is Dumbledore thinking? I think Fred and George are right, he really is getting senile." Rigel heard Ron say as he approached, leaving him slightly surprised, but not too much.
It became clear that those three had stumbled upon that room on the third floor, of course they had, Rigel knew that the event was connected to Draco, but at that point, Draco wasn't that interested in Potter anymore, at least not these days, the boy was still depressed because of the broom, every now and then he saw him trying to convince Snape to return the broom.
Rigel knew that the so-called 'duel at midnight' in the trophy room, as in the original, did not take place, so they didn't have to run from Filch and end up finding the room with Cerberus. Even so, Rigel wasn't worried, the fact was that Dumbledore wanted Harry to find the room, so it was never a matter of 'chance'.
Rigel regretted it somewhat, he had thought this event would bring him some reward, but he ended up losing it.
At that moment, noticing Rigel approaching, Hermione cleared her throat loudly to remind the two idiots.
She didn't do it to hide Cerberus, she just didn't want the others to know that she broke the rules with those two idiots.
Although the adventure took place during the day this time, the fact is that the third-floor hallway was off-limits, simply wandering there could get them into trouble, or worse! They could lose points from the house!
Knowing McGonagall, this was quite possible, a large part of the reason Gryffindor lost points was the woman herself. While the other professors would only ease the students with mild verbal warnings, McGonagall, on the other hand, preferred a much more direct style of discipline.
She would get furious and deduct points, then get even more furious because she had to deduct points.
In any case, Rigel had already heard everything, his senses far better than that little witch had expected. Harry didn't mind when he saw it was Rigel, but Ron wanted to keep it a secret completely, this was supposed to be an adventure between him and Harry, and he didn't want to share it.
As for Hermione? Sorry, who?
Therefore, when he saw Harry about to speak, he made a constipated expression, clearly meaning for Harry not to say anything.
Harry was clearly confused and torn, thankfully, Rigel wouldn't let that little red-haired boy have an easy life.
"A three-headed dog? Is that what's on the third floor?" He asked 'curiously' as he sat down next to Harry.
The three of them looked shocked, how did Rigel know that?
"How did you...?" Hermione couldn't help but ask, only to control herself at the last moment, afraid someone else might hear.
"I have very good ears." Rigel shrugged, picking up a loaf of bread from the table and biting into it, yes, it was great as always, soft and warm.
The three stared at him expressionlessly. Ron almost wanted to jump up and say that he was spying on them, but luckily even the idiot realized that it was probably his fault, after all, he was the one talking.
Hermione's irritated look at him clearly showed that she thought the same.
Harry didn't much care, saying. "Yes, it really was a huge dog, it had three fierce heads, the saliva dripping from it was enough to fill several of Filch's buckets!"
Rigel chuckled softly and shook his head. "It must be a Cerberus, they're native to Greece, very dangerous creatures, I must say. Their magical defense is extreme, even a killing curse would only tickle it."
"The killing curse?" Harry asked curiously. New to the wizarding world, he still had no idea about the three unforgivable curses.
Hermione wasn't confused, although she was new, she had already read the wizarding laws. The three unforgivable curses were at the top, so she had firmly imprinted that in her mind, even more so after learning about their effects.
Ron paled as he spoke about it, he knew about curses too, though little, the marks of dark wizards. Rigel speaking about it so calmly only made him more certain that Rigel must be a dark wizard.
Rigel ignored Ron's suspicious glances as he explained the three curses to Harry.
Harry, upon hearing the effect of each one, was completely terrified.
In young Harry's mind, magic was something to transform a table into a pig or unlock a door, but Rigel's description made young Harry realize just how dangerous dark wizards are in advance.
Hermione took advantage of the moment while Harry adjusted to the change in his perception of the wizarding world to speak. "I don't know if you idiots noticed, but there was clearly a trapdoor above Cerberus, he was clearly protecting something."
"Oh, sorry, I was too preoccupied with the heads to look at the paws!" Ron said, annoyed. He was already in a terrible mood because of Rigel, and now that he'd found an outlet, he took it out on Hermione.
Hermione was clearly resented by the way Ron spoke to her.
Her little face formed an annoyed pout as she picked up her books, not even glancing at the food while stomping away.
Harry looked at Ron with exasperation. He felt that what Ron had done was wrong, but he didn't want to be too harsh on Ron, after all, he was the first friend he'd ever had.
Ron was bothered by Harry's gaze, but in the end, he just snorted and looked away, grabbing a chicken leg and chewing forcefully, taking out his unhappiness on the dead bird.
Rigel shrugged, uninterested in resolving these 'disputes', instead, he took some butter and spread it on his bread. He was hungry. Harry, watching them eat, also sighed and began to devour his food.
Rigel said goodbye to them shortly after, taking a portion of food on a plate and carrying it with him to the library. Neville was probably there, and since he would likely forget about dinner, Rigel would simply bring it to him.
Honestly, sometimes he felt that being friends with Neville was like having a pet, luckily, he knew how to use the bathroom by himself.