# Water is Thinner

You might need to know this before I begin:

Riddle me this:

I am connected to pressure,
Much like what I am behind,
As air passes through them whichever;
Greatest when keys are combined.
I am connected to flow.
Never am I in a glass.
At sight of a vampire, go!
Their teeth look at me and surpass.
I remain blue, red or green.
Or sometimes I may turn to violet.
Nin, bin and then for marine,
Scientists end with the triplet.

What am I?

Hopefully this riddle proves to be more difficult than my previous one.

I will provide just one hint.

Hint:

When drank I am toxic, believe it or not!
But without me, eventually, you will start to rot.

My vowels come once in the place of a winner.
The rest win in breakfast, lunch and dinner.

Water is thinner.

I haven't figured out every single clue, but I'm pretty sure you are

BLOOD.

I am connected to pressure,

Blood pressure.

Much like what I am behind,
As air passes through them whichever;

I think this is referring to the lungs (air passes through the lungs, transferring oxygen to the blood) but I'm not altogether sure.

Greatest when keys are combined.

No idea what this is about. [EDITED to add:] It turns out -- see OP's comments -- that this is the bit for which it's relevant that your skin is in some sense your largest organ. When you combine keys with air passing through pipes (I confess I don't really see what "them" is referring back to, or what "whichever" is doing) you get a (pipe) organ, and "what I am behind" (the skin) is the "greatest" (= largest) organ.

I am connected to flow.

Blood flows through your circulatory system.

Never am I in a glass.

No idea what this is about. (It's certainly possible to put blood in a glass, and of course there's e.g. the Bloody Mary cocktail...) [EDITED to add:] OP explains in comments that since drinking blood is a bad idea, you wouldn't put it in a glass. Which indeed you wouldn't, but I bet someone has at least once :-).

At sight of a vampire, go!
Their teeth look at me and surpass.

Vampires are bloodsuckers, and if you saw one and knew it for what it is you would probably pale (the blood leaving your face) with fear.

I remain blue, red or green.

Blood is actually red. The nobility are said to have "blue blood", supposedly because their indoor lifestyle would have given them more visible veins, which appear blue by contrast with the redder surrounding flesh. There is an extremely rare medical condition in which blood turns green; I don't know whether that's what the last bit of this is about, though.

Or sometimes I may turn to violet.

There are some marine animals with violet-coloured blood.

Nin, bin and then for marine,
Scientists end with the triplet.

Nope, can't parse this. [EDITED to add:] OP explains in comments that this is alluding to haemocyanin, haemoglobin, and the fact that it's marine animals that have green and violet coloured blood. (Sulfhemoglobinemia was not in view here after all.)

The hint:

When drank I am toxic, believe it or not!

Yup, drinking blood is not a good idea.

But without me, eventually, you will start to rot.

It won't take very long.

My vowels come once in the place of a winner.

Perhaps because the only vowel in BLOOD is O, and there is exactly one O in PODIUM, or in GOLD. [EDITED to add:] OP explains in comments that "in the place of a winner" means "in the word formed by the first letters of the lines", that word being IMAGINATIONS -- which is another word with exactly one O in it.

The rest win in breakfast, lunch and dinner.

The consonants are B,L,D, the first letters ("winners") of those words.

Water is thinner.

Old proverb: "Blood is thicker than water".

• Rot13$[$Lbh tbg gur nafjre, ohg fbzr ernfbavatf ner vapbeerpg. Svefgyl, "nf nve cnffrf guebhtu" gnyxf nobhg nve cnffvat guebhtu cvcrf, naq jura lbh pbzovar xrlf(sebz n xrlobneq), vg orpbzrf na betna. Guhf, gur evqqyr vf fnlvat gung gur nafjre vf oruvaq gur "terngrfg" (ynetrfg) betna, juvpu vf lbhe fxva. (Whfg yvxr oybbq). Sbe gur "ava, ova" cneg, gurfr ner raqvatf bs fpvragvsvp jbeqf gb qrfpevor gur pbybhef bs oybbq.$]$ Go to the link, (compoundchem.com/wp-content/uploads/2014/10/…), to see what I mean. To be continued... – Mr Pie Jul 14 '18 at 23:53
• ...Also, since it is toxic to drink, I thought it would never be in a glass (because nobody would drink it). I am young, so I have never had a cocktail, and although it could be in a glass, I did not see any reason. Sorry. Finally... Rot13$[$...gur jvaaref ner gur yrggre va "svefg cynpr" (cynpr bs n jvaare) juvpu ner gur pncvgny yrggref. Gurl fcryy VZNTVANGVBAF naq gur ibjry "B" nccrnef bayl bapr (nf fnvq va gur uvag, "B" orvat gur nafjre'f ibjryf). Jvgu gur "O,Y,Q" cneg, lbh tbg gung pbeerpg, naq chggvat gurz gbtrgure znxrf OYBBQ. Ohg fgvyy, pbatenghyngvbaf!$]$ – Mr Pie Jul 15 '18 at 0:02
• Woops, I forgot to accept the answer. Sorry about that :\ – Mr Pie Jul 16 '18 at 1:55

Partial answer, as I haven't figured out how it fits all of the riddle. I'm pretty sure the answer is:

Mercury

I am connected to pressure,

Mecury is used in old manometers

Much like what I am behind,
As air passes through them whichever;
Greatest when keys are combined.
I am connected to flow.

Mercury is used in some flowmeters.

Never am I in a glass.

You don't store mercury in a glass unless you wan't to get poisoned.

At sight of a vampire, go!
Their teeth look at me and surpass.

Play on words, mercury is also known as quicksilver and vampires are supposed to be afraid of silver.

I remain blue, red or green.
Or sometimes I may turn to violet.

One can find this colours on the thermometers denoting different temperatures.

Nin, bin and then for marine,
Scientists end with the triplet.

• Rot13$[$Avpr gel, ohg hasbeghangryl, gur nafjre vf abg zrephel. V qb yvxr lbhe pyrire guvaxvat, fb V fhttrfg lbh xrrc gelvat vs lbh jnag. Yvggyr tvirnjnl: gur jbeq VZNTVANGVBAF vf uvqqra va gur evqqyr. Pna lbh svaq vg?$]$ – Mr Pie Jul 14 '18 at 12:26
• @user477343 "Nice try, but unfortunately, this is not the answer. I do like your clever thinking, so I suggest you keep trying if you want. Little giveaway: there's a word hidden in the riddle. Can you find it?" - would have made a fine comment without needing encoding. I think rot13 comments have their place, but we don't want walls of them on every post. Please try to avoid them unless they're actually necessary. – Rubio Jul 15 '18 at 18:40
• @Rubio $\diamondsuit$ ok. I will only use Rot13 if the answer word for word is in the comment. Thanks for clarifying :) – Mr Pie Jul 15 '18 at 23:03