I shall say in advance that this is a nitpicking thread, so please don't take it too seriously.
So. In Suikoden 2 we are presented with the exciting opportunity to introduce our current hero Riou to our previous hero Tir McDohl and see two legendary leaders fighting alongside eachother.
But let's look at how this meeting takes place.
assuming that Gremio was revived at the end of S1 and you have it saved on your memory card that you used to transfer data onto S2, then it is Gremio himself who is blocking your path to Tir, protecting his master's privacy while he is fishing peacefully. You enlist the help of the young fanboy Ko to cause a diversion so that Gremio moves from his spot, allowing you access to Tir. And, if you have at least one returning S1 character in your party, he or she will step up and say hello to Tir, and introduce you to him.
WAIT A MINUTE
Why didn't one of my returning characters speak to gremio in the first place? Was it too much for Hix/Tengaar/Viktor/Flik/Futch/Stallion/Meg etc. etc. to pipe up and say "Hey, Gremio, it's me! How have you been? Is Tir with you? Can we say hello?" or have these people all forgotten gremio? I could understand some characters like Hix and Tengaar not recognising gremio, but i remember Viktor being pretty f#cking upset about losing Gremio. It was Viktor who retrieved Gremio's axe after he died so he could hand it to Tir as a keepsake, and he even demanded that Tir avenge Gremio's death when you made the decision to spare Milich.
and yet at this moment, Gremio is a perfect stranger to all of them. He doesn't think "oh, this young man is accompanied by former allies of the young master, some of whom risked their very lives to protect him and help him gain victory in my absence. Perhaps I should let them pass to say hello to the young master." No, but he'll run off and ditch the young master at the sound of a boy he barely knows screaming from the hills.
Now I'm not surprised at Gremio for running off to help a boy in distress - it's his protective nature kicking in. It's what made him so loyal to Tir. We also know our Gremz isn't very aware of other people around him. Remember how when we got home at the beginning of S1, and Gremio was fussing over Tir and didn't even notice Teo standing there in his own house? I guess it was similar in this situation. He only noticed Riou standing in front of him, and not any of the others standing there thinking "WTF, Gremio?? Stop ignoring us." I'll bet when they do reach Tir and the black screen of conversation occurs, they would have said something like "Gremio hasn't changed much, then."
Of course, if Gremio was not revived then it is Ellie standing there preventing Riou and friends from meeting tir, and she runs off to find her little brother. Sheena/Futch/Meg/Tengaar or whoever could have easilly said to ellie "We know that guy, we devoted our lives to him three years ago, now GTFO of our way." but that wouldn't have been very nice if the next State hero was wandering around with a gang of bullies who push little innkeeper's daughters around.