\documentclass{standalone}

\usepackage{tikz}
\usetikzlibrary{calc}
\usetikzlibrary{positioning}

\newcommand*{\connectorH}[4][]{
  \draw[#1] (#3) -| ($(#3) !#2! (#4)$) |- (#4);
}
\newcommand*{\connectorV}[4][]{
  \draw[#1] (#3) |- ($(#3) !#2! (#4)$) -| (#4);
}

\begin{document}

\begin{tikzpicture}[every node/.style={draw, minimum size=1cm, thick, fill=white}]
  \node[] (a) {A};
  \node[above right=1cm and 2cm of a] (b) {B};
  \node[below right=1cm and 2cm of a] (c) {C};

  \connectorH[->, red]{0.50}{a}{b}
  \connectorH[->, blue]{0.75}{a}{c}
\end{tikzpicture}

\end{document}
