[Soundwave is aware how quiet his footsteps are, and he uses that to his advantage. Not just doing missions where stealth is required, but also just to mess with people by sneaking up on that, albeit unintentional most of the time except for that one scare he gave to Monika earlier.

Regardless if it's intention or not, it's never not amusing to see the shocked and surprised faces he typically get when nobody expected him. Props to Monika for not screaming. Honestly, he was kinda prepared for it, but he can drink in the dumb face she's making. Maybe now she knows he can probably sneak up on her like he did before, except in his big mech body, complete with a scary, big shadow looming over her. Trust that it's bound to happen in the future.

That amused look he's giving her turns into a slightly offended face when she called him a jerk, though.]

What did I do? You said I can come up here, and so I did.

[And then, he gives her a dead-eyed stare when she insinuated that he did something naughty without her looking. His real body will remain offline for now to conserve energy.]

Yes, I did. I looked through your drawers to search for your poem and- [He reaches for her pillow and hugs it around his arms, bringing it slightly up to hide half of his face.] -I hugged one of your pillows because I missed your sweet smell so much... Idiot.

[Then, he throws said pillow at her.

Okay, he absolutely didn't the first one, but he at least did actually hug her pillow at least while he was daydreaming about Monika and thinking happy thoughts.]

Of course I did not do anything naughty, stupid Monika.