Brothers a Tale of Two Sons

After saving the turtles in Chapter 6 follow the woman and she will stop by a tree, head up the hill to the left and keep going until you get to the bench at the top of the hill, get both boys over to the bench and interact with it and they will sit down and cutscene will kick in and the achievement will pop.

This guide will walk you through all of the achievements in just 2 hours, timestamps are below the video


ACHIEVEMENTS LIST TIMESTAMPS
0:00 – Intro and Prologue
3:27 – Take a Break Achievement
10:37 – Chapter 1
10:57 – Wishing Well Achievement
14:39 – Love Birds Achievement (Part 1/2)
15:00 – Bunny Buddies & Black Sheep Achievements
24:14 – Chapter 2
42:45 – Chapter 3
44:06 – Falling Star Achievement
51:55 – Chapter 4
52:15 – A Sad Tune Achievement
58:00 – Windpipe Achievement
59:50 – Love Birds Achievement (Part 2/2)
1:14:03 – Chapter 5
1:18:00 – Call of the Giants Achievement
1:23:34 – Chapter 6
1:24:06 – Behind the Curtain Achievement
1:28:10 – Turtle Soup Achievement
1:30:45 – Whale Song Achievement
1:38:04 – Chapter 7
1:54:26 – Epilogue