Here's the book I was given, and I definitely recommend it. I get lots of ideas for fast, simple projects just browsing through it!
Theres a book called Mega Mini Cross Stitch which seems popular and has a huge variety of little patterns in.
Otherwise it’ll probably just be a case of going on pinterest and searching for patterns or samplers individually.
I have a book, “Mega Mini Cross Stitch” by Makoto Oozu. It has just what you’re looking for. I got it on amazon.
ETA link:
I’ve recommended Makoto Oozu’s books a few times since the patterns are both tiny and fun.
Mega Mini Cross Stitch: 900 Super Awesome Cross Stitch Motifs https://www.amazon.com/dp/1910904384/ref=cm_sw_r_cp_api_glc_fabc_Stz3FbTF1GBGC
Makoto Oozu has two Greg books of miniature patterns that will help with the pattern planning part.
Mega Mini Cross Stitch: 900 Super Awesome Cross Stitch Motifs https://www.amazon.com/dp/1910904384/ref=cm_sw_r_cp_api_i_o6llFbFTK1WDW
Pattern from Mega Mini Cross Stitch
Pattern from Mega Mini Cross Stitch
I would suggest getting your brother a small/beginner cross stitch kit to start. etsy in particular has loads of custom kits available in all kinds of styles and are often very reasonably priced; you should be able to pretty easily find something to suit his tastes. I also think this book from amazon would be really fun for a beginner:
Stitching on clothing is totally doable but requires a waste canvas and can be a little tricky so I wouldn't recommend it as a first project.
Makoto Oozu’s books are also a great resource for tiny designs: Mega Mini Cross Stitch: 900 Super Awesome Cross Stitch Motifs https://www.amazon.com/dp/1910904384/ref=cm_sw_r_cp_api_glc_fabc_L7.1FbA06P89V
Patterns for macarons from my new book Mega Mini Cross Stitch: 900 Super Awesome Cross Stitch Motifs https://www.amazon.com/dp/1910904384/ref=cm_sw_r_cp_api_glc_fabc_7ZWZFbMGNASFE?_encoding=UTF8&psc=1 The rest is freehand
Patterns for octopus and scissors from my new book Mega Mini Cross Stitch: 900 Super Awesome Cross Stitch Motifs https://www.amazon.com/dp/1910904384/ref=cm_sw_r_cp_api_glc_fabc_7ZWZFbMGNASFE?_encoding=UTF8&psc=1 The rest is freehand
I already had Tardis' pattern, you can get it here https://cloudsfactory.net/10th-doctor-and-rose-tyler-doctor-who.html
Ladybug comes in this book I just bought https://www.amazon.com/Mega-Mini-Cross-Stitch-Awesome/dp/1910904384