Thatch starts noticing changes in Marco's behaviour soon after the phoenix comes back from a trip to Paradise. At first, Thatch doesn't take much notice. They are after all small, easily overlooked things. Marco was never the most expressive of his brothers in the first place, and the changes he witnesses now are no different. If Marco hadn't been the closest thing to a best friend he ever had, he might have missed it entirely.

He first notices something is afoot the very moment Marco places a foot on the Moby Dick. While the blonde man's face is as impassive as usual, Thatch can feel the man is not in the best of moods. The atmosphere around him is heavy as Marco stalks past him. He rather looks like the only thing he wants is to walk right past without a word of acknowledgment, but he stops anyway and turns to greet Thatch.

The cook puts it down to fatigue and kindly asks if Marco would like him to bring some food to his room. Marco shakes his head warily muttering he feels too tired. Thatch's gaze follow his brother as he disappears inside the ship. Then, Ace falls overboard and Thatch forgets all about it.

The next morning Marco is back to normal, and Thatch gives it no further thought. That is, until he catches his oldest brother standing on deck one night, frozen next to the railing, eyes lost into the vague. Marco is perfectly immobile and he doesn't seem to notice Thatch approaching him at all. Concerned, the cook advances towards him but stops as the man's expression come into view. There's something distant in the way he gazes out at the ocean as if he's looking for something there as far away as it is intangible. Marco looks almost like a lost child and Thatch suddenly feels like he might be intruding. He gives his brother a last glance and tiptoes back inside.

He never speaks of it but it stays in his mind and after that he starts noticing more. How Marco stops in his work sometimes to look out to sea as if hearing something nobody else can. It only last a moment and he is soon back to work, as if nothing ever happened and no one is the wiser. Except Thatch who waits for those moments like a beast stalking its prey. There are also those mornings when Marco walks in the galley looking dark. On those particular days, most of their brothers take care to stay well out of his way and it is up to Thatch to make sure Marco does not just toy with the food in his plate but eats as well.

Then one day, Thatch has the misfortune of making a woman related joke and Marco glares at him. It's not the usual shut-your-mouth-you-idiot glare but a full-blown I'm-going-to-pull-your-heart-out-of-your-throat-if-you-don't-shut-up-right-now glare. Thatch has never found himself confronted to such a murderous expression on Marco's face and his mouth shuts with a click. Without a word, Marco pulls himself away from the arm Thatch has thrown around his shoulders and stalks away moodily. Thatch never mentions women or love in front of Marco again.

After that particular occurrence, Thatch decides to give the man and his problems a wide birth. He does want to know what is up with the First Mate, and if possible help him out too, but he doesn't want to lose his life doing it, thank you very much.

He has almost given up on ever knowing what causes Marco strange moods when Ace brandishes a rookie's wanted poster and announces loudly that this is his little brother before launching into a stream of information on the young grinning pirate. Thatch is listening distractedly, amused by Ace's very obvious brother complex when he catches sight of Marco looking at the wanted poster with a faint smile playing on his lips. Thatch has to pinch himself because he can count on one hand the number of times he has seen Marco smiling so disarmingly.

His lips slowly stretch in a grin as understanding washes over Thatch. He doesn't know when it happened or even how, but Marco clearly knows Ace's little brother and if his newly acquired quirks are to be believed, he may very well have a thing for the kid. Thatch swells up in pride at the realization. He has always known Marco to be a loner, someone who looked at others from afar and the fact that this man has finally found someone he can look at with such adoration makes Thatch giddy with happiness. It is then and there that he appoints himself as the guardian angel of Marco and his young lover – or crush…or whatever.

From that day on, he makes sure that every article about Strawhat Luffy reaches Marco and he even manages to 'lose' one the kid's wanted poster near Marco's room. He is glad to see when he passed by the man's door an hour later, that the poster has disappeared. He listens more attentively when Ace talks about his little brother so that he can tell Marco some of those things as well, and Marco might grumble that it never ends with both Ace and Thatch harping him on about the kid, but there's a shadow of a smile on his face and he always listens to the end.

When Thatch finds himself lying in a pool of his own blood, betrayed by a brother and slowly slipping away from the world of the living, he starts thinking about Marco and his boy, how he wouldn't be able to watch over them anymore, and how Ace was going to be so angry when he found out. A smile made its way to his lips. That was bound to be hilarious, it made him wish he could see it. Then Marco was at his side calling his name in a panic and Thatch was grinning at him, looking up fondly at his favourite brother.

"I hope you can meet him again." he tells him, sight blurring and his grip on reality loosening. "I'm glad." he murmurs, and closes his eyes to the world.