[name_f]Mariana[/name_f] Tatum/ [name_u]Taytum[/name_u]
[name_f]Mariana[/name_f] [name_u]Oakley[/name_u]
[name_f]Mariana[/name_f] [name_u]Blair[/name_u]
[name_f]Mariana[/name_f] [name_u]Leighton[/name_u]
Which is your favorite? And feel free to give some suggestions 
I love Mariana! It’s very sweet and summery to me, so I prefer Blair with it than your other choices, which sound nice but feel a bit too modern with Mariana!
Maybe:
Mariana Blythe
Mariana Belle
Mariana Daisy
Mariana Colette
Mariana Cleo
Mariana Eve
Mariana Everly
Mariana Juliet
Mariana Phoebe
Mariana Scout
Mariana Tess
Mariana Winter
Mariana Zelie
Mariana Zadie
[name_f]Mariana[/name_f] is lovely! [name_f]My[/name_f] favourite is [name_f]Mariana[/name_f] [name_u]Oakley[/name_u]. Some ideas in line with the gender neutral feel of the MNs you like:
[name_f]Mariana[/name_f] Oaklan/Oaklyn, [name_f]Mariana[/name_f] [name_u]Blakeley[/name_u], [name_f]Mariana[/name_f] [name_u]Linden[/name_u], [name_f]Mariana[/name_f] [name_u]Morgan[/name_u], [name_f]Mariana[/name_f] [name_u]Evan[/name_u], [name_f]Mariana[/name_f] [name_u]Finley[/name_u], [name_f]Mariana[/name_f] [name_u]Riley[/name_u], [name_f]Mariana[/name_f] [name_f]Willodean[/name_f].
[name_f]Mariana[/name_f] is lovely 
For me [name_f]Mariana[/name_f] feels elegant, ethereal, whimsical and has this gothic fairytale vibe perfect for an enchanting Victorian dark academia story. I love [name_f]Mariana[/name_f]!
I think for me I would love to feed into this dark fairytale vibe from your suggestions I think [name_u]Blair[/name_u] fits the bill the best but I do prefer [name_u]Blaire[/name_u] spelling wise.
You’ve had a lots of suggestions so count any repeats as me being in agreement with the berries
[name_f]Mariana[/name_f] [name_f]Zadie[/name_f]
[name_f]Mariana[/name_f] [name_u]Willow[/name_u]
[name_f]Mariana[/name_f] [name_u]Solstice[/name_u]
[name_f]Mariana[/name_f] [name_u]Winter[/name_u] or even [name_f]Mariana[/name_f] Midwinter
[name_f]Mariana[/name_f] [name_u]Wilde[/name_u]
[name_f]Mariana[/name_f] [name_f]Frostine[/name_f]
[name_f]Mariana[/name_f] [name_f]Colette[/name_f]
[name_f]Mariana[/name_f] [name_f]Delphi[/name_f]
[name_f]Mariana[/name_f] [name_u]Winslow[/name_u]
[name_f]Mariana[/name_f] [name_f]Capri[/name_f]
[name_f]Mariana[/name_f] [name_f]Violet[/name_f]
[name_f]Hope[/name_f] this helps
[name_f]Mariana[/name_f] [name_u]Blair[/name_u] is great!
[name_f]Mariana[/name_f] [name_u]Lennox[/name_u], [name_f]Mariana[/name_f] [name_u]Hadley[/name_u] and [name_f]Mariana[/name_f] [name_u]Quincy[/name_u] came to mind!
I have [name_f]Mariana[/name_f] [name_f]Elle[/name_f] and [name_f]Mariana[/name_f] [name_f]Rose[/name_f] on my list! I also like [name_f]Mariana[/name_f] [name_u]Blair[/name_u]!
[name_f]Mariana[/name_f] [name_u]Blair[/name_u] is lovely!
[name_f]Mariana[/name_f] [name_u]Blair[/name_u] is my favorite!
Other ideas, for fun:
[name_f]Mariana[/name_f] [name_u]Bailey[/name_u]
[name_f]Mariana[/name_f] [name_u]Brighton[/name_u]
[name_f]Mariana[/name_f] [name_f]Eisley[/name_f]
[name_f]Mariana[/name_f] [name_u]Elliott[/name_u]
[name_f]Mariana[/name_f] [name_u]Emery[/name_u]
[name_f]Mariana[/name_f] [name_u]Harper[/name_u]
[name_f]Mariana[/name_f] [name_u]Holland[/name_u]
[name_f]Mariana[/name_f] [name_f]Kinley[/name_f]
[name_f]Mariana[/name_f] [name_u]Parker[/name_u]
[name_f]Marianne[/name_f] [name_f]Pyper[/name_f]
[name_f]Mariana[/name_f] [name_u]Remi[/name_u]
[name_f]Mariana[/name_f] [name_u]River[/name_u]
[name_f]Mariana[/name_f] [name_u]Scout[/name_u]
[name_f]Mariana[/name_f] [name_u]Shelby[/name_u]
[name_f]Mariana[/name_f] [name_u]Sutton[/name_u]
I love [name_f]Mariana[/name_f], and my favorite middle with it is [name_u]Blair[/name_u]. I think the A sounds just flow together so well and I like the longer first name with the short, sweet one syllable middle. That being said, I actually love all of the options you listed! I think my second favorite is [name_f]Mariana[/name_f] [name_u]Tatum[/name_u], but I personally think I would actually just go with [name_f]Mariana[/name_f] [name_u]Tate[/name_u]. That has the same short snappiness as [name_u]Blair[/name_u].