When it came to breaking school rules, Fred and George truly had a wealth of experience. Professor Sprout never even saw them.
Although she and Hagrid later patrolled the area, it wasn't enough to warrant searching the student dormitories.
The only thing that upset Silvan was that Professor Sprout had become much more attentive to the Whomping Willow.
For a long time afterward, Silvan sneaked out through the secret passage more than once, hoping to repeat his trick and gather a few more Whomping Willow branches, but every attempt failed.
Before he could even get close to the Whomping Willow, he would receive Tom the scout's shrill warning cry.
That meant someone was nearby—perhaps Professor Sprout, perhaps Filch, or someone else. In any case, it wasn't safe.
Silvan would then return to the castle as quickly as he could.
Fortunately, no one suspected anything... Cats were among the pets permitted at Hogwarts, so hearing a cat meow at night was perfectly normal.
Even so, Silvan was still furious.
It was all Fred and George's fault, those reckless idiots. Otherwise, he could have gotten at least another two or three branches!
So whenever Silvan saw the two of them, he never gave them a pleasant look. Fred and George had no complaints about it whatsoever, because the two brothers really had held him back.
After all, Silvan had managed to bring back such a long branch without a scratch, while they had returned empty-handed and even drawn Professor Sprout's suspicion.
In the end, their skills simply weren't good enough.
Still, after that incident, their relationship with Silvan did grow closer, as though they had met far too late.
In Fred's own words, "The Sorting Hat is ridiculously reliable. Silvan is a natural Gryffindor."
Naturally, that only made Silvan angrier, and he