What other names come to mind? What combinations can you think of? And what nicknames could we use?
(The spellings are standard where I’m from.)
I’m really looking forward to your thoughts and opinions. 
Adrian
Anton
Cornelis
Frederik
Hendrik
Jonathan
Joris
Levin
Linus
Magnus
Mattis
Maximilian
Miro
Nikolas
Rafael
Simon
Stellan
Theodor
Zacharias
I’m always a fan of [name_m]Rafael[/name_m] and [name_m]Frederik[/name_m]. I like [name_m]Hendrik[/name_m] too. [name_m]Rafael[/name_m] [name_m]Hendrik[/name_m] or [name_m]Frederik[/name_m] [name_m]Miro[/name_m] might be my picks.
I love so many of those! I could choose [name_m]Magnus[/name_m] [name_m]Hendrik[/name_m], [name_m]Simon[/name_m] [name_m]Frederik[/name_m], [name_m]Rafael[/name_m] [name_m]Miro[/name_m] or [name_m]Nikolas[/name_m] [name_m]Jonathan[/name_m].
I love [name_m]Anton[/name_m], [name_m]Cornelis[/name_m] (this spelling is new to me, I like it!), [name_m]Linus[/name_m], [name_m]Miro[/name_m], [name_m]Rafael[/name_m], [name_m]Stellan[/name_m], and [name_m]Theodor[/name_m]!
[name_m]You[/name_m] have a great list! We have a very similar taste. [name_m]Lovely[/name_m] to see someone else like Cornelis/Cornelius too, [name_m]Cornelius[/name_m] is a family name for me so it’s very precious!
Your list takes me to my happy place! I especially love [name_m]Frederik[/name_m], [name_m]Miro[/name_m], [name_m]Maximilian[/name_m], [name_m]Simon[/name_m], [name_m]Magnus[/name_m], and [name_m]Cornelis[/name_m]. I would love to meet a little [name_m]Frederik[/name_m] [name_m]Miro[/name_m], [name_m]Simon[/name_m] [name_m]Magnus[/name_m], [name_m]Simon[/name_m] [name_m]Cornelis[/name_m], [name_m]Magnus[/name_m] [name_m]Anton[/name_m], or [name_m]Maximilian[/name_m] Miro/Miro [name_m]Maximilian[/name_m]! Good luck!
Some nn ideas:
[name_m]Adrian[/name_m] - [name_m]Rian[/name_m]
[name_m]Cornelis[/name_m] - [name_m]Neil[/name_m], [name_f]Nel[/name_f]
[name_m]Hendrik[/name_m] - [name_m]Hendry[/name_m], Henik
[name_m]Jonathan[/name_m] - [name_m]Nathan[/name_m] - saw this idea on here recently
[name_m]Magnus[/name_m] - [name_m]Mage[/name_m]
[name_m]Mattis[/name_m] - [name_m]Mats[/name_m]
[name_m]Maximilian[/name_m] - Mill, [name_m]Miller[/name_m], [name_m]Mills[/name_m], [name_f]Lian[/name_f], [name_m]Mal[/name_m]
[name_m]Nikolas[/name_m] - [name_m]Klaus[/name_m]
[name_m]Rafael[/name_m] - [name_m]Raffy[/name_m] (obvious but so sweet!)
[name_m]Stellan[/name_m] - [name_m]Stan[/name_m]
[name_m]Theodor[/name_m] - [name_m]Ted[/name_m]
[name_m]Zacharias[/name_m] - Zachrie
Some combos with nns:
[name_m]Adrian[/name_m] [name_m]Joris[/name_m] / [name_m]Anton[/name_m] [name_m]Joris[/name_m] “AJ”
[name_m]Linus[/name_m] Jonantha / [name_m]Levin[/name_m] [name_m]Joris[/name_m] “LJ”
My personal favourites on your list are [name_m]Joris[/name_m], [name_m]Levin[/name_m], [name_m]Miro[/name_m], [name_m]Mattis[/name_m], [name_m]Nikolas[/name_m] and [name_m]Rafael[/name_m] 
Some combos I particularly like:
[name_m]Theodor[/name_m] [name_m]Mattis[/name_m]
[name_m]Miro[/name_m] [name_m]Cornelis[/name_m]
[name_m]Stellan[/name_m] [name_m]Zacharias[/name_m]
[name_m]Stellan[/name_m] [name_m]Magnus[/name_m]
[name_m]Rafael[/name_m] [name_m]Miro[/name_m]
[name_m]Nikolas[/name_m] [name_m]Miro[/name_m]
[name_m]Nikolas[/name_m] [name_m]Anton[/name_m]
These are so handsome!
Oh wow, thanks to everyone for your replies!
You’ve come up with some great combinations. I particularly liked…
[name_m]Frederik[/name_m] [name_m]Miro[/name_m]
[name_m]Rafael[/name_m] [name_m]Miro[/name_m] (sounds like an artist)
[name_m]Magnus[/name_m] [name_m]Anton[/name_m] (sounds antique, stately, and strong)
[name_m]Adrian[/name_m] [name_m]Joris[/name_m] (I like how the ‘r’ and ‘i’ are echoed in the middle name)
[name_m]Anton[/name_m] [name_m]Joris[/name_m]
My absolute favorite for a first name has always been [name_m]Theodor[/name_m] “Theo.”
But I haven’t found a combination for it yet that really wows me. I’m looking for a name that softens Theodor’s sternness a bit—something that makes it seem a little more youthful and playful, without being too silly.
Do you have any ideas?
I like [name_m]Frederik[/name_m], [name_m]Hendrik[/name_m], [name_m]Joris[/name_m], [name_m]Linus[/name_m], [name_m]Magnus[/name_m], [name_m]Simon[/name_m] & [name_m]Theodor[/name_m]!
Nice list! I especially love [name_m]Miro[/name_m] and [name_m]Stellan[/name_m] 
Combos:
[name_m]Adrian[/name_m] [name_m]Linus[/name_m]
[name_m]Rafael[/name_m] [name_m]Miro[/name_m]
[name_m]Stellan[/name_m] [name_m]Theodor[/name_m]
[name_m]Hendrik[/name_m] [name_m]Maximilian[/name_m]
[name_m]Magnus[/name_m] [name_m]Anton[/name_m]
Nicknames -
[name_m]Anton[/name_m] “Tony”
[name_m]Cornelis[/name_m] “Cory”
[name_m]Frederik[/name_m] “Freddy”
[name_m]Hendrik[/name_m] “Hank”
[name_m]Jonathan[/name_m] “Johnny”
[name_m]Joris[/name_m] “Jory”
[name_m]Maximilian[/name_m] “Max”
[name_m]Nikolas[/name_m] “Niko”
[name_m]Rafael[/name_m] “Rafa”
[name_m]Theodor[/name_m] “Theo” or “Teddy”
[name_m]Zacharias[/name_m] “Zack”
Maybe…
[name_m]Theodor[/name_m] [name_m]Rafferty[/name_m]
[name_m]Theodor[/name_m] [name_m]Felix[/name_m]
[name_m]Theodor[/name_m] [name_m]Ivo[/name_m] or [name_m]Yvo[/name_m]
[name_m]Theodor[/name_m] [name_m]Marijn[/name_m]
[name_m]Theodor[/name_m] [name_m]Milan[/name_m]
[name_m]Theodor[/name_m] [name_m]Sascha[/name_m]
[name_m]Theodor[/name_m] [name_m]Xandar[/name_m]
[name_m]Theodor[/name_m] [name_m]Sohan[/name_m]
[name_m]Theodor[/name_m] [name_m]Luan[/name_m]
[name_m]Theodor[/name_m] [name_m]Elliot[/name_m]
[name_m]Theodor[/name_m] [name_m]Nino[/name_m]
[name_m]Theodor[/name_m] [name_m]Finn[/name_m]
[name_m]Theodor[/name_m] [name_m]Remy[/name_m]
[name_m]Theodor[/name_m] [name_m]Kasper[/name_m]
[name_m]Theodor[/name_m] [name_m]Frans[/name_m]