I'd love to hear more about this. Any idea who it was?
Sorry for the late response on this one, been a bit busy over Christmas.
This would have been probably 2014. I wasn't there for the whole thing, and some of this has been reconfirmed by people who were also there, but from what I remember he was obsessed with a friend from a Sonic website (we will call him D) and their girlfriend (we will call her L).
L was quite a controlling person, and effectively isolated D from most of their friends as she deemed them to be "toxic", despite never meeting or speaking them She was deep into the 2014 tumblr white wannabe angry feminist thing, and had some weird views on things. To each their own, I guess.
At first they were happy for him to join them at times watching anime, etc, but eventually it got to the point that he would have autistic meltdowns over them wanting alone time together to talk/watch stuff.
So, D and L eventually blocked him on everything and asked him to leave then alone forever. He then did the same things to them like sending gifts of games, contacting them with alt accounts, sending presents in the mail, etc.
He started having constant emotional breakdowns in calls over this, and eventually even went to the doctors over it to get himself on anti depresants (yes, I'm fucking serious) despite his other friends advising him against it. He couldn't take the side effects for more than 12 hours and never took another one again.
The stalking continued. Eventually after a while, D and L made callout posts on Tumblr and he somewhat backed off, but the emotional breakdowns in the calls still happened until his friends got tired of it and got rid of him.
D and L broke up around the same time because of D's own degeneracy coming to light. He begrudgingly accepted Spanner back into his life, but him and his other friends never let Spanner forget just what a fucking creep they were during the whole saga. Some of them probably will have been the Sonic people who came to talk about Spanner to this Vtuber recently.
Over the years there has been other little obsessions, but not to the point that it got to with those two... until now, obviously.
When the thread started, he freaked out and "came clean" to all of his friendship groups, which is how his Sonic people found out. It has been pointed out to him that if he had just shut up and left it alone, most of his online life would have never known about this whole situation. He's not very smart.
Whenever his remaining "friends" have been calling his actions out, his response is apparently "but I haven't done anything as bad as this for nearly 10 years!!!!". Same group also report that he nearly lost his job over the summer as he couldn't concentrate and kept crying in work calls because of this Vtuber and her Mods "bullying and blocking him". Should tell you everything.
Apparently Spanner is active in this thread and has been reading everything written about himself. He linked the initial callout post which was then shared to me, which is why I am now here. He indirectly brought me here to tell you things about him. Funny.
Even with all the above said, I find it very unlikely that he would actually try to visit her in real life, as the guy is effectively an emotionally stunted shut in who leaves the house a few times a year. I also still very much doubt he came on the tablet, as amusing as that makes the whole thing. He very much does need serious emotional therapy.
If I remember anything else or hear of anything more I will come back and post again. Enjoy your new year!