How to draw "arrow labels" on arrows

Question

I would like to draw a graph like this, with "arrow labels" (the blue edges and e_1, e_2, and e_3 labels) on top of the arrows: I can always just use coordinate to hack it, but I'm wondering if there are easier methods.

Answer 1

\documentclass[tikz,border=10pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{decorations}
\pgfdeclaredecoration{simple line}{initial}{%<------https://tex.stackexchange.com/a/216086/197451
  \state{initial}[width=\pgfdecoratedpathlength-1sp]{\pgfmoveto{\pgfpointorigin}}
  \state{final}{\pgflineto{\pgfpointorigin}}
}
\tikzset{
   shift left/.style={decorate,decoration={simple line,raise=#1}},
   shift right/.style={decorate,decoration={simple line,raise=-1*#1}},
}
\begin{document}
\begin{tikzpicture}[]
    \tikzstyle{every node} = [circle, fill=red!30]
    \node (a) at (0, 0) {A};
    \node (b) at +(0: 5) {B};
    \node (c) at +(60: 5) {C};
    \foreach \from / \to in {a/b, b/c, c/a}
        \draw [->] (\from) -- (\to);
    \path[-&gt;,blue] (a) edge[shift left=4pt, shorten &gt;=3em, shorten &lt;= 3em] node[fill=none, above]{$e_2$}(b);

\path[->,orange] (b) edge[shift left=4pt, shorten >=3em, shorten <= 3em] node[fill=none, below]{$e_2$}(a);
\end{tikzpicture}
\end{document}