Help, my life is in danger!

Question

So I was sitting in this nice little pub minding my own business when this party of 6 people walked in and sat down at the table next to me. The group looked kind of odd.

• There was this woman with Platinum blonde hair and purple eyes. Her clothes seemed kind of burnt too.
• A guy with dark hair was all dressed up in fur, like he came from a very cold place.
• Then there was another blonde woman, she kinda gave of this vibe like the others were beneath her and her clothing was very fancy, expensive looking.
• Opposite of her was a man, tall, proud looking, royal in a way, but still he seemed just and fair.
• Another man in the group was poor looking, his boots were still wet just as were the bottom of his pants. He was very easily aggravated during the discussions they had.
• The last one was a woman with a much darker skin tone, (barely) dressed in leather. I did notice she had a strange accent.

They argued for a while about something, I wasn't able to hear about what but it seemed important to them. Like they all wanted the same thing. Suddenly they all went quiet as they noticed I was looking at them, then each one wrote something on a piece of paper. The blonde woman came to my table and said this:

"It is not a good idea to stare at people. We don't like you and we have decided to kill you unless you prove you are worthy."

Then she gave me those six pieces of paper and said: "In one week we will be back, tell us what these say or lose your head." Then all of them left the pub.

The pieces of paper made no sense to me, so I hope you can help me:

• 251731 - 4520122 - 22510 - 251731 - 452254222515 - 22510 - 251731 - 4514141113 - 22510 - 1652241411103
• IODINE, JOLIOTIUM, NOBELIUM, NOBELIUM, NORWEGIUM, NITROGEN, OXYGEN, OXYGEN, POTTASIUM, THORIUM, TIN, TUNGSTEN, TUNGSTEN, URANIUM, YTTRIUM
• ANEWPHELIRAAIBASAYYSTNTLSSDS
• 9d2c6s5d8s6s9h8s9d7h4c9h8s3d3h8s9dJh2cKh7h
• GVDYRBDJOG
• DIIJOKJUSTGEORUTWODQOKLTJOK

One more thing, as I was leaving, I noticed one more piece of paper near the table they were sitting at. It said: "Sometimes you need an animal to go on!"

Hint 1:

Each message is encrypted with a different technique. Although sharing a common theme all are independent of each other.

Hint 2:

Three messages require a password to decipher. Figuring out who the people in the story are, aids in figuring out the passwords.

Hint 3:

2c = A, 2s = N, 5d = D, Jh = W

Hint 4:

Character to Family - Phrase to Character - Animal connected to Family = Key

Hint 5:

Last two messages require a key to encrypt, both keys have the same length

Answer 1

Until I deciphered the first phrase I assumed that the descriptions of the people were in the same order as the phrases. But it seems that

person 1 belongs to phrase 6 and vice versa.

Since M Oehm already solved phrase 1, 2, 3 and 4, I'll only post the decryptions of the last two. I was only able to do these with hints 4 and 5.

---

Code GVDYRBDJOG

The text is decrypted with Vigenère cipher with the keyword "KRAKEN", which is the animal on the coat of arms of House Greyjoy. The decrypted text says WEDONOTSOW, which are the words of house Greyjoy.

So the phrase is.

We Do Not Sow

---

Code DIIJOKJUSTGEORUTWODQOKLTJOK

The encryption method is substitution cipher with plaintext \begin{align*}\text{ABCDEFGHIJKLMNOPQRSTUVWXYZ}\end{align*} translating to ciphertext \begin{align*}\text{DRAGONBCEFHIJKLMPQSTUVWXYZ}\end{align*} The text decrypts back to ALLMENMUSTDIEBUTWEARENOTMEN. This is a line spoken by Daenerys Targaryen.

So the phrase is

All men must die, but we are not men.

Answer 2

In a comment to the question, squeamish ossifrage remarked that ...

... one of the ciphers is a transposition cipher and that tere seems to be a Game of Throne theme. Both observations are correct. The messages seem to decode to phrases from the series.

I know next to nothing about Game of Thrones and according to the hints, three messages require keys. These keys are probably the names of some of the characters described in the story.

Number sequence

This look as if the words were just the positions letters in the alphabet pasted together, e.g. THE = 20 + 8 + 5 = 2085. The numbers are in the range from 0 to 7. This may suggest octal encoding or a base-9 encoding. In the latter case, the alphabet will fit nicely into the range 01 to 28.

The words 251731 and 22510 both occur three times and lend a certain structure to the sentence. I first thought that they might be and and the to give something like "The something and the other thing and the something else." In any case these are probably common short words.
It turns out that the encoding is octal:

    0                 1                 2                 3
    0 1 2 3 4 5 6 7   0 1 2 3 4 5 6 7   0 1 2 3 4 5 6 7   0 1 2
    . a b c d e f g   h i j k l m n o   p q r s t u v w   x y z

The possibilities for the two words above are then:

    2 2 5 · 1 0          2 5 · 1 7 · 3 1
    b b e   h            b e   a g   c a
    b u--                u--   o--   y--
    r-- e

The gaps inside the number blocks indicate places where a number can't span over two digits, because the two-digit combo doesn't form a valid number from the decoding table above.

The words are obviously "you" and "her" backwards. Pursuing this avenue further (but this time not fussing about with several possibilities), we get:

    4 5 20 122    4 5 225 4 2225 15    4 5 14 14 1113    16 5 224 14 1110 3
    d e p   ar    d e r e d r u  m     d e l  l  i k     n  e r d l  i h  c

The phrase is:

You raped her. You murdered her. You killed her children.

Chemical elements

The chemical symbols of the listed elements are:

  I/J Jo No No Ng N O O K/Po Th Sn W/Tu W/Tu U Y/Yt

The slashes mark alternative symbols as given in the list of elements linked by the OP. These symbols were proposed at some time, but are not official. Joliotium and Norvegium aren't official names of elements.

Anyway, it turns out that the alternatives aren't needed and the symbols can be rearranged to:

  Y O U K No W No Th I Ng Jo N Sn O W

The phrase is:

You know nothing, Jon Snow!

Code ANEWPHELIR ...

This message was decoded by squeamish ossfrage. It is a transposition cipher. The message has 28 letters, which can be arranged in a 7×4 grid:

      ↓ A  N  E  W  P  H  E
        L  I  R  A  A  I  B
        A  S  A  Y  Y  S  T
        N  T  L  S  S  D  S

The decoded message can now be read column-wise.

The phrase is:

A Lannister always pays his debts.

Number/letter code 9d2c6s5d8s6s ...

The string is made up of alternate numbers and lower-case letters, except in two places, where the numbers are replaced by J and K. There are only four lower-case letters: c, d, h and s.

This suggests playing cards where the numbers and J, Q, K and A are the card face and c, d, h and s represent one of the four suits. With the help of the hint, we can create a decoding table:

                       2 3 4 5 6 7 8 9 X J Q K A
     clubs/diamonds    A B C D E F G H I J K L M
      hearts/spades    N O P Q R S T U V W X Y Z

The phrase is:

Hard truths cut both ways.

Code GVDYRBDJOG

Not decoded yet.

Code DIIJOKJUSTGEORUTWODQOKLTJOK

Not decoded yet.

This could be a Vigenère cipher. There are two occurrences of JOK, 21 letters apart, which may suggest a key length of either three or seven.