I wonder if you will ever draw Astro Boy's siblings. The is Uran his little sister who tends to get into trouble, she can be very stubborn and is based on Astro's blueprints.
There's Cobalt, Astro's prototype and big brother, he is lanky and tall. He is a bit clumsy and forgetful, he is considered dimwitted but csn be very creative when in the right situation. The 63s anime series improved him a lot more than the Manga did. Cobalt was actually interesting in that seriously even getting some stand alone episodes and a bit of character development. Cobalt will gladly help his little brother with anything, including fighting bad guys. He is a surprisingly good help too.
There is Reno Astro's human big brother from the 2003 series, Reno was raised in a robot circus and as such is very smart enough to fix Astro amd understand Astro's blueprints and a great acrobat being agile and flexible enough to climb a building. Don't underestimate the tan little kid just because he is human. He can definitely a bit cocky but he shares the same believes about humans and robots as Astro. Also I adore that despite Cobalt and Reno being the same age, they don't look the same. Reno is smaller than Cobalt and has more chubbiness on his cheeks making him look young, in other words Reno still has his baby fat, although Astro has more baby fat. Reno also goes through some character arcs and character development in the series.
And there is Astro Kitty from Go Astro Boy Go, he is Astro's little brother and despite being cat, he is a robot so he can stand on to lega and talk. He is very hyperactive always ready to play or go on a mission. Which can cause him to be one traci minded, he is also hotheaded which doesn't help. When calm though he is very kindhearted kitten who loves and looks up to Astro Boy. Plus I like his design and the fact he has claw, a canon that shoots bouncy balls, and a machinical arm with random objects including a mallet. He is fun.
Sorry for the rant. I just feel like Astro's siblings don't get much attention and that they deserve more. Especially Cobalt, Reno, and Astro Kitty, they get very little attention.
No worries and Thank you! I love a good long read about anything astro boy related :) I'll give a long response in return if that is okay.
About your question, I have drawn Astro's siblings before, at some even being my favorite characters before it became Atlas. I really like cobalt in specific, and agree with everything you mentioned. His character would have been perfect for the 80s adaptation. Considering that the show leans to a more slice of life theme, it would have been wholesome to see all Astro's siblings (including chiitan) interacting with each other, maybe even help astro if he needs a hand.
Reno... I haven't drawn that boy not even once ever. (Sorry to Reno fans) He's an amazing character no doubt about it. I certainly can brainstorm ideas and scenarios of Reno and Astro wich is easy due to them being so alike (only difference is robot and human races). Don't think I don't like Reno just because I never drew him. I don't take art requests at the moment, but if enough people do want to see a little Reno drawing done by me, I can do it!
Astro kitty is Astro's sibling!!!? (I dont know why I am so surprised they have the same abilities and blueprints. I had the impression that they're just separate robot boys? That's my rather stupid thinking taking over) I haven't caught up to Go Astro Boy Go only finishing half of it.
One thing I really do love is how tezuka accurately portrays siblings in his works. I'm the eldest bro in my family with sisters and a younger brother, so I awfully relate to Astro when he looks over his younger sister. (Especially when the occasional fights occur to the point one gets so upset.) In each painting or doodle I have of astro with his siblings, has a part of my own childhood too.
You see me draw uran in her 80s outfit and everyone knows how much I draw Atlas. Astro boy 80s in specific is such a comforting show to me, it perfectly blends the life of a little robot superhero with some wholesome and relatable family moments. Maybe this explains why I never drawn other known astro boy siblings outside of the 1980s. Which I should though, it feels like neglect. No siblings should be left out.
Once again thank you for this question! After writing this, it made me realize how little art I've shown publicly about Astro boy and his siblings. So here are some to conclude this long but fun response!